31 1961 - SLAC National Accelerator Laboratory · High-power waveguide components ..... A . Mark ... 2. Coupler geometry for reducing field ... second circular boring of the coupler

TWO-MILE ACCELEWTOR PROJECT

A.E.C. Contract AT(04-3)-363

Status Report

1 October t o 31 December 1961 M Report No. 294

January 1962

Stanford Linear Accelerator Center Stanford University Stanford, California

h-oprietory data of Stanford University and/or U. S. Atomic Energy

Recipient hereby agrees not t o publish the within informa- Commission.

t i o n without spec i f ic permission of Stanford University.

Nothing i n t h i s permission s h a l l be construed as a warranty o r

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S t a t e s Government t h a t exercise of the permission o r r i g h t s herein

granted w i l l not in f r inge patent , copyright, trademark o r o ther r i g h t s

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unpatented processes, ideas o r devices o r t o use any copyrighted

ma te r i a l a r e here in granted by implication, es toppel o r otherwise

except t o the ex ten t revealed by the t echn ica l data and information,

t he subjec t of t he permission herein granted.

TABU3 OF CONTENTS

I . Introduction . . . . . . . . . . . . . . . . . . . . . . . I1 . MarkIVprogram . . . . . . . . . . . . . . . . . . . . .

I11 . Accelerator structure and high-power waveguide component s tudies . . . . . . . . . . . . . . . . . . . . A . Radiofrequency studies of the accelerator structure . B . Electroforming . . . . . . . . . . . . . . . . . . . . C . Brazing . . . . . . . . . . . . . . . . . . . . . . . D . Water jacket . . . . . . . . . . . . . . . . . . . . .

IV . Inject ion system . . . . . . . . . . . . . . . . . . . . . E . High-power waveguide components . . . . . . . . . . .

A . Mark IV conversion program . . . . . . . . . . . . . . B . Comparison of two basic types of in jec tors . . e . C . G u n specif icat ions . . . . . . . . . . . . . . . . . . D . Two-element buncher . . . . . . . . . . . . . . . . .

V . Microwave c i r c u i t s . . . . . . . . . . . . . . . . . . . . A . General rf s tudies . . . . . . . . . . . . . . . . . . B . Drive system . . . . . . . . . . . . . . . . . . . . . C . Phasing system . . . . . . . . . . . . . . . . . . . .

V I . Klystron s tudies . . . . . . . . . . . . . . . . . . . . .

B . Research and development subcontracts . . . . . . . . C . New f a c i l i t i e s . . . . . . . . . . . . . . . . . . . . D . L i f e t e s t s . . . . . . . . . . . . . . . . . . . . . . E . Experimental tubes . . . . . . . . . . . . . . . . . . F . Planning the klystron procurement . . . . . . . . . . G . Klystrons on Mark N . . . . . . . . . . . . . . . . .

V I 1 . High-power klystron windows . . . . . . . . . . . . . . . A . Window-life t e s t stand . . . . . . . . . . . . . . . . B . Recirculator windows . . . . . . . . . . . . . . . . . C . Other window work . . . . . . . . . . . . . . . . . .

V I 1 1 . Modulator s tudies . . . . . . . . . . . . . . . . . . . . A . Project development a c t i v i t i e s . . . . . . . . . . . .

A . Tube complement and performance . . . . . . . . . . .

15

15 15 17 17 24 26 31 31

32

32 33 34 34 35 36 36 36 39 41 41

. ii .

. .

. . . . . . . . . . . . . . . . . . . . . . . 1x . Vacuum system A . Mark IV conversion . . . . . . . . . . . . . . . . . . B . Feasibility studies . . . . . . . . . . . . . . . . . . C . Problem studies . . . . . . . . . . . . . . . . . . . . D . Conclusions . . . . . . . . . . . . . . . . . . . . . .

X . . . . . . . . . . . . . . . . . . . A . Site earth-movement studies . . . . . . . . . . . . . . B . Support C . Alignment

. Support and alignment

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

XI . Control system studies . . . . . . . . . . . . . . . . . . A . . . . . . . . . . . . . . . . . . . . . General studies

B . Design studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C . Trigger system

XI1 . Research area design . . . . . . . . . . . . . . . . . . .

B . Current investigations . . . . . . . . . . . . . . . . XI11 . Site, buildings and utilities . . . . . . . . . . . . . . .

A . Major conventional facilities . . . . . . . . . . . . . B . Special problems . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . A . Work completed

. . . . . . . . . . . . . . . . . . . . . . . XIV . Water system . . . . . . . . . . . . . . . . . . . . . . A . Plantwater

. . . . . . . . . . . . . . . . . . . . . B . Coolingwater

C . Blow-down water D . Research and development . . . . . . . . . . . . . . .

XV . Heating and ventilating . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . .

Page

43 43 43 43 44 45 45 45 45 47 47 47 48 54 54 54 58 58 59 60 60 60 61 61 62

LIST OF FIGURES

1. A comparison of structure phase variations immediately

after tuning and 17 months la ter . . . . . . . . . . . . . . 2. Coupler geometry fo r reducing f i e l d asymmetries . . . . . . 3. A = deflection of the inside w a l l of the disk-loaded

waveguide f o r 49.7 ps i t o t a l pressure A comparison of measured and computed phase change vs

efiernal pressure fo r a 2rr/3 10-ft uniform accelerator

s t ructure . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . 4.

3a. Space-harmonic amplitude and t o t a l r / Q as a function of

normalized group velocity.

0.230, 0.120, and .060) . . . . . . . . . . . . . . . . . . (For various d isk thicknesses:

3b. Corrected r / Q fo r space harmonic as a function of

normalized group velocity. (For various d isk thicknesses :

0.230, 0.120, and .060 i n ) . . . . . . . . . . . . . . . . . 6. Phase s h i f t e r B: phase s h i f t (9) vs ambient temperature

at various currents (ima) . . . . . . . . . . . . . . . . . Phase s h i f t e r B:

at temperatures 82'~, 102'F, and 118'F . . . . . . . . . . . 7. inser t ion lo s s i n db vs current (ima)

8. Half-wave disk N o . 6 . . . . . . . . . . . . . . . . . . . . 9. Fai lure of b e r y l l i a window . . . . . . . . . . . . . . . . .

10. B e r y l l i a window assembly . . . . . . . . . . . . . . . . . . 11. Trigger pulse d i s t r ibu t ion . . . . . . . . . . . . . . . . . 12. Detail of selector un i t . . . . . . . . . . . . . . . . . .

6 7

10

11

18

29

30 38 38 40

51

52

- i v -

I.

I. INTRODUCTION

This Status Report covers t h e work from 1 October 1961 t o 31 December

1961 under Atomic lhergy Commission Contract AT( 04-3)-363, held by Stan-

ford University. This contract or iginal ly covered the period from

1 September 1960 t o 30 June 1961, and has now been extended t o 31 March

1962. Since Ju ly 1, 1960, the Status Reports f o r t h i s contract have

been combined with those f o r Contract AT( 04-3)-21, Project Agreement No. 1.

Contract AT(04-3)-21, P. A. 1 ended November 30, 1961, and a Final Report

of i t s work has been issued.

The objectives of Contract AT(O4-3)-363 include the i n i t i a l design,

engineering and development work f o r t h e Stanford two-mile l i nea r elec-

t ron accelerator . Among the spec i f ic objectives are master planning of

t h e accelerator s i t e , buildings and laboratories; development of compo-

nents and subsystems; and t h e procurement of t e s t models of par t icu lar

components t h a t w i l l lead t o i n i t i a t i o n of construction without delay.

The Mark IV accelerator has been converted t o a model section of t he pro-

posed two-mile accelerator , incorporating those components and techniques

intended f o r l a t e r use with t h e la rger machine.

The two-mile accelerator project , now ca l led t h e Stanford Linear

Accelerator Center, w i l l soon begin i t s construction program.

t i o n w i l l be divided i n t o two par ts :

r e l a t ed technical environment; and ( 2 ) t h e more conventional work asso-

c ia ted with s i t e preparation, buildings, s t ructures , u t i l i t i e s , e t c . To

assist with t h e l a t te r a c t i v i t i e s , Stanford has retained t h e services,

under subcontract, of t h e f i r m Aetron-Blume-Atkinson, a j o i n t venture

consis t ing of Aetron, a divis ion of Aerojet-General Corporation; John A.

Blume and Associates, Engineers; and t h e Guy F. Atkinson Company. I n

these reports t h i s architect-engineer-management f i r m i s of ten referred

t o as "ABA."

Construc-

(1) t h e accelerator i t se l f and i ts

- 2 -

TI.

11. MARK I V PROGRAM

The Mark I V acce lera tor conversion prograh was continued during the

quar te r and a t year end i s considered t o be e s sen t i a l ly complete. following chronology presents t he highl ights of t he period.

The

1. The e l ec t ron gun w a s i n s t a l l e d October 20th, and t h e cathode

was ac t iva ted . A t e s t showed a microperveance of one.

2. Modulator tests were conducted during ear ly November, and

peak vol tages i n excess of 200 kv were applied t o t h e klystrons.

Further t es t s and modifications of t h e dr ive system w e r e made.

3. On November l o t h , rf w a s put i n t o the acce lera tor sect ions f o r

t he f irst t i m e . Considerable outgassing w a s observed i n t h e vacuum

system. Similar runs a t gradually increased power l eve l s were con-

ducted la te r i n t h e month. Access t o t h e trench w a s not permitted

on these occasions. Radiation surveys indicated safe work conditions

i n t h e u p s t a i r s equipment room with only partial trench shielding i n

place. The f i n a l shielding blocks were i n s t a l l e d i n ea r ly December

according t o plan.

4. Gun-pulsing tes ts w e r e conducted on November 20th and 21st

with s a t i s f a c t o r y r e s u l t s .

5. The f i rs t beam w a s achieved on t h e machine a t 1 :OO p.m.,

December 8 t h , a f te r severa l hours of s t a r t -up preparations.

operation w a s reasonably smooth, although considerable t rouble w a s

experienced with t h e col l imators s t i ck ing both i n and out of t h e beam

path.

The

6 . A second run w a s conducted on December 14th pr imari ly f o r

confirmatory purposes. The maximum beam energy during stable opera-

t i o n w a s estimated a t 50 Mev, with an average beam current of .65 pa,

as ind ica ted by the in - l ine Faraday cup. ( I n s t a l l a t i o n of t h e beam

de f l ec t ion system i s under way and w i l l be t e s t e d a t a la te r da t e . )

Radiation readings taken a t various loca t ions adjacent t o the trench

sh ie ld ing were a t o r below 1 mr/hr.

The gradual t r a n s i t i o n t o an operat ional s t a t u s during t h e

quar te r required t r a i n i n g and reor ien ta t ion of personnel i n t h e Mark I V

organization. This w a s accomplished by means of information sessions,

- 3 -

11 I

participation in shakedown tests and direct experience during beam

operation.

accommodate the experimental-test program commencing in January of It is anticipated that crew and machine will be ready to

1962.

- 4 -

111.

III. ACCELERATOR STRUCTW AND HIGH-POWER WAVEGUIDE COMPONENT STUDIES

A. RADIOFREQUENCY STUDES OF THE ACCEURATOR STRUCTURE

1. Structure Measurements and Tuning

a, S t a b i l i t y of tuning

A n ind ica t ion of t h e s t a b i l i t y of tuning w a s obtained by measure-

ments on a 21r/3 electroformed section tuned i n June 1960. shows the phase var ia t ions about the i n i t i a l reference posi t ion of one

arm of a Smith-plot presentation.

good, and the re does not appear t o be any var ia t ion between the measure-

ments t h a t would indicate e i t h e r a uniform o r random detuning of the

cav i t i e s .

va r i a t ion i n ambient conditions during t h e measurements.

differences noticeable as the shorting plunger i s withdrawn fur ther

down the sec t ion a re t o be expected because of the increasing e f f ec t

of var ia t ions i n ambient conditions and inaccuracy i n the determination

of n u l l posi t ions.

l imited

on Mark IV and being tuned by indenting the w a l l with a l/b-in. rounded

plunger, t h e tuning i s s tab le f o r periods t o 1-1/2 years.

Figure 1

The correspondence i s seen t o be

The differences t h a t appear a re probably the result of The l a rge r

While the significance of a s ingle t e s t must be

it appears that , f o r electroformed sections now being used

Further t e s t s of tuning s t a b i l i t y under various processing and

storage conditions w i l l be undertaken.

b o Symmetric f i e l d couplers

P a r t s a re being made t o determine dimensions f o r a matched

coupler with minimized f i e l d asymmetry along radial l i n e s about t h e

axis. simulate the boundary conditions of the coupler i n the back wall of

the cavi ty , This would r e s u l t i n an unnecessarily complex geometry.

A suggestion by G. A. b e w and 0. Altenmueller, which w a s promising

i n terms of both ease of fabr ica t ion and e l e c t r i c a l charac te r i s t ics ,

i s being investigated.

which i s produced by taking a cut at the o r ig ina l diameter and o f f se t

a dis tance x, opposite the coupling iris.

To obtain the desired result ,one would idea l ly attempt t o

Figure 2 shows the change i n coupler geometry,

c. Observations of temperature and humidity e f f e c t s on measurement s

The previous report mentioned that the temperature i n the RF Test

- 5 -

<

I I I I I I I I I I

/

- 6 -

111.

x = the offset from the accelerator axis of the second circular boring of the coupler

FIG. 2--Coupler geometry for reducing field asymmetries.

- 7 -

11x0

Room w a s being controlled t o w i t h i n 14OF. t h a t can be achieved i n a room of t h i s type and usage.

change i s a larger var ia t ion than desired for s t ructure measurements,

and addi t iona l s t ruc ture temperature control w a s considered,

found, however, t h a t the 10-ft sections effect ively integrate tem-

perature f luctuat ions, and section temperatures can be kept acceptably

constant without the use of temperature-controlled jackets o r similar devices.

T h i s i s probably the bes t

This temperature

It w a s

Humidity var ia t ions, however, continue t o pose problems. Er ra t ic

measurements have been observed a s a r e su l t of humidity changes that

occurred more than eight hours previously. This slow propagation of

humidity e f f e c t s can be avoided by c i rcu la t ing f i l t e r e d room air

through t h e section.

from gradual changes i n room humidity during measurements.

some of these d i f f i c u l t i e s , we a re considering the poss ib i l i t y of

making measurements and tuning w i t h a moderate

within t h e section.

D r i f t s i n data have a l so been observed t o r e s u l t

To avoid

mtn Hg) vacuum

2. Resonant-Structure T e s t s

The first t e s t i n t h i s s e r i e s was an attempt t o compare outgassing

caused by high f i e l d s and by diss ipated power.

system w a s found t o be

independent of the rf leve ls . T h i s in te res t ing r e s u l t demonstrates

the establishment of a nearly-ideal reference condition. We are con-

s ider ing exposing cav i t i e s t o various standard "dir ty" conditions f o r

fu ture t e s t s .

3. Calculations have been made t o determine pr incipal e l a s t i c de-

The pressure i n the

2 x lo-' mm Hg (pumped by a Vacion 5L pump)

Dependence of Phase on External Pressure

formations of the w a l l and the disks of the disk-loaded waveguide,

The ca lcu la t ions of the radial deflections were made by coupling the

general theory of cy l indr ica l she l l s w i t h the theory of thick-walled

cyl inders ,

between ex terna l and in t e rna l pressure t o be

The def lec t ions given are changes i n radial dimensions; they are one- half of the changerr i n diameters.

All t he calculat ions were car r ied out assuming a difference

35 p s i + 14.7 p s i = 49.7 psi .

Loads and def lect ions a re proportional throughout the e l a s t i c

range, The following p l o t s w i l l , therefore, give deflections fo r any

- 8 -

111.

pressure i f t he proper pressure r a t i o i s applied t o the p lo t ted values.

Deflection of the waveguide wall f o r one cavi ty of the constant-

a t tenuat ion sect ion i s p lo t ted on Fig. 3. This p lo t gives approxi-

mately

49.7 p s i t o t a l pressure.

th ick d i sk w i l l have a r a d i a l def lect ion of 10.0 x in .

16.8 X loW6 in. max r ad ia l def lect ion a t the mid-span f o r

A t t h i s pressure the hole i n the .23O-in.

Calculation of the r a d i a l def lect ion of the w a l l has a l so been

car r ied out f o r a thinner d isk .121-in. thick, assuming t h i s disk does

not buckle. The center distance, 1.378 in. between disks, i s the same

as i n t h e e a r l i e r case. The maximum deflection a t the middle of the

span between d isks i s 20.71 x in . , and the corresponding r a d i a l

def lec t ion of t he hole i s 13.4 x lom6 in.

For t h e constant-gradient sect ion the 0.d. i s kept constant a t

4,000 in . , while the i .d . var ies from 3.2884 in . f o r the first cavi ty

t o 3.2190 i n . f o r the 87th cavity.

cavi ty has been calculated at 17.33 x cavi ty a t 16.21 x in . The assumption t h a t the def lect ion var ies

l i n e a r l y would, i n most cases, be su f f i c i en t ly accurate.

The max def lect ion of the first

in . , and f o r the 87th

Measurements were m a d e of the change i n phase resu l t ing from

the appl ica t ion of external pressure t o an electroformed 2n/3 uniform

section.

o r very near ly a f u l l 10- f t sect ion length.

r e s u l t of computations o f deflect ion, which indicated t h a t an appre-

c iab le e f f e c t on the propagation constant would result from the

appl ica t ion of pressures required f o r some cooling methods tha t are

being considered.

Changes i n t o t a l phase s h i f t were measured over 80 cavi t ies ,

The t e s t s were made as a

The phase s h i f t expected from the predicted def lect ion of the

inner w a l l and d i sk hole i s shown i n Fig. 4 along with the phase

measurements.

21(/3 uniform sect ions by pressurizing the water jacket.

were electroformed.

The la t te r were taken on one of the origi’nal Mark N These sections

It i s clear t h a t applying moderate pressure t o the accelerator w a l l

can cause s ign i f i can t amounts of phase s h i f t . It i s in t e re s t ing t o

consider t h e phase change possible as a r e s u l t of barometric-pressure

- 9 -

t - - - -----.,-

I I- A - --- -

- - - - - - ,

- c.-- _ -

Note: radlal deflection of hole in disk: + = 10.0 x in.

I

.230 in. -

FIG. 3 - - A = deflection of the inside wall of the disk-loaded waveguide for 49.7 psi total pressure.

- 10 - 1

- * - - -

1.378 in. -c

11s.

I I I I I I I 0 10 20 30 40 50 60 70 /

-

-

-

- from deflection

@'---measured points

( w a l l thickness = 3/8-in

FIG. 4--A comparison of measured and computed phase change vs external pressure for a 2fi/3 10-ft uniform accelerator structure.

- 11 -

variat ions. A change of 1 i n . i n barometric pressure w i l l r e su l t i n

a change i n absolute pressure of 1/2 p s i and a phase e r ro r of .07°/section.

4. High-Power RF-Test Area

Detailed plans were made for a high-power t e s t area. Early full-

power t e s t s of the accelerator struciture and waveguide components w i l l

be car r ied out here.

t h a t for the resonant-structure t e s t s . Preparation f o r t h i s move has

begun.

The first equipment t o be located here w i l l be

5 . Establishment of a Frequency Standard

The need f o r a frequency standard was considered, along with

A s a re su l t , we are obtaining a high- systems f o r sa t i s fy ing it.

s t a b i l i t y o s c i l l a t o r and very l o w frequency ( v l f ) receiver and com-

parison equipment.

determination a re high accuracy i n a given time ( 5 p a r t s i n lo9 i n one

hour), simplicity, and r e l a t ive ly low cost.

The advantages of the v l f system f o r frequency

B . ELECTROFORMING

The s m a l l f a c i l i t y f o r e lec t ropla t ing 10- f t lengths has been

f inished f o r some time. A Universal p l a t ing rack tha t w i l l hold the

10- f t sect ion halfway immersed i n the p la t ing solution has a lso been

finished.

the 10- f t sections at speeds from 0-to-100 rpm, and a variable-speed

agate burnishing mechanism.

The rack includes a variable-speed gear motor t h a t can tu rn

A 10- f t dummy w i l l be t r i e d out i n the last pa r t of 1961 and

the f i rs t sect ion i n the beginning of 1962.

C. BRAZING

The 10- f t vertical . brazing furnace has been Fompleted and has

been t e s t e d w i t h dumqy pieces of disk-loaded waveguide consisting of

s t r a igh t copper tubing. It has performed sa t i s f ac to r i ly , and we ex-

pect t o braze the first 10-f t lengths ear ly i n the next quarter.

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111.

D. WATER JACICET

The reduced-pressure-boiling t e s t setup was completed, and preliminary

t e s t s performed, The tes t runs have indicated t h a t the instrumentation

is sa t i s fac tory and t h a t t he basic system is capable of operating over

the desired range of conditions. However, some d i f f i c u l t y w a s experienced

i n maintaining the reduced pressure and a uniform heat input. A new

pressure-control system has been obtained and ins ta l led . The heat-input

method has been modified i n order t o obtain a more uniform heat-input

d i s t r ibu t ion , and the system i s ready f o r tes t ing .

The small-scale, cross-flow-test mockup w a s s e t up and t e s t s per-

formed. The tests have shown conclusively t h a t unless an extremely

la rge amount of water i s used, the cross-flow method of cooling the

accelerator cannot meet the 2 1 / 4 O F temperature-control requirement.

A water jacket has been designed f o r use w i t h constant-attenuation

accelerator sect ions. The same basic jacket design w i t h minor modifi-

cat ions can be used f o r the constant-gradient accelerator. In t h i s

design a constant flow of water t r a v e l s a spiral path along the ac-

ce l e ra to r tube f o r t he constant-attenuation case. For constant-gradient

operation the same flow path i s used, but the water-flow rate i s in-

creased as the flow progresses along the accelerator tube.

The drawings and spec i f ica t ions for t h i s jacket ( f o r both appli-

cat ions) have been completed. The jacket i s intended t o be used as a t e s t vehicle f o r developmental tests of other accelerator components.

It probably w i l l not be used f o r the two-mile accelerator, because it wouldbe d i f f i c u l t t o fabr ica te and t o i n s t a l l .

Another promising water-Jacket concept is current ly being invest i -

gated. In t h i s cooling method, 18 one-half-inch 0.d. tubes are brazed

d i r e c t l y onto the surface of the accelerator.

d i rec t ion through a l l tubes f o r constant-attenuation sections, and i n

opposite d i r ec t ions i n adjacent tubes f o r constant-gradient sections.

T h i s method appears t o have the advantage of s implici ty of fabr icat ion

and i n s t a l l a t i o n over a l l o ther schemes considered. Test samples a re

being made t o determine the p o s s i b i l i t y of brazing the tubes i n a s ingle

operation i n the v e r t i c a l brazing furnace.

t h i s concept has been designed and is current ly being fabricated.

Water flows i n one

A t e s t system t o e v e u a t e

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E n HIGH-POWER WAVEGUIME COMPONENTS

Primary emphasis i s being placed on t h e development of a waveguide-

vacuum valve.

and with low-level microwave measurements, Additionally, a fu l l - sca l e

mockup of t he separation between the klystron ga l le ry and t h e acce lera tor

enclosure i s under construction,

t he performance of the waveguide connection between the klystrons and

the accelerator . Further, the setup w i l l be used f o r the development

of i n s t a l l a t i o n procedures.

Two spec i f ic designs a r e being evaluated ana ly t i ca l ly

This setup w i l l allow the t e s t i n g of

The i .d. cross sect ion fo r the waveguide has been set at 2.840 in . x 1.340 i n .

y e t t o be determined,

The w a l l thickness and method of cooling have

- 14 -

r

Iv.

I V . I N J E C T I O N SYSTEM

A. MARK I V CONVERSION PROGRAM

The Mark I V gun and gun modulator operated s a t i s f a c t o r i l y during

the i n i t i a l beam t e s t i n g of t h e Mark I V accelerator . The gun current

was measured t o be 15 pa average with a f i rs t anode pulse of approxi-

mately 4 kv, and a cathode pulse of 75 kv.

B. COMPARISON OF TWO BASIC TYPES OF INJECTORS

Two types of i n j ec to r s have been proposed f o r Project M.

1. The i n - l i n e in j ec t ion system i n which a hollow cathode gun'

is located on the a x i s of t h e accelerator .

2. The i n f l e c t i o n (of f -ax is ) i n j ec t ion system.

A study of t h e f e a s i b i l i t y , comparative advantages and cos t s of these

two systems has been undertaken and w i l l continue during t h e next

quarter .

will be s u b s t a n t i a l l y less f o r an on-axis i n j ec to r than f o r a n in f lec t ion-

type in j ec to r .

The cos t study ind ica tes t h a t t h e i n s t a l l e d cos t per i n j ec to r

C. GUN SPECIFICATIONS

Preliminary spec i f ica t ions f o r a conventional type gun have been

prepared. A survey of tube and gun manufacturers has been i n i t i a t e d t o

see i f a s tock gun e x i s t s t h a t meets these spec i f ica t ions .

D. TWO-EZEMEl" BUNCKER

Tentat ive choice of a buncher has been made pending: (1) a de ta i l ed

numerical i n t eg ra t ion t o evaluate t h e e f f e c t of space harmonic and

r a d i a l fo rces , and ( 2 ) an experimental test .

two elements and,should bunch 8& of t h e in jec ted electrons i n t o a phase

i n t e r v a l of 35' t h a t will form a 3 O bunch i n t h e f i rs t 1 0 - f t sec t ion of

acce lera tor . The f irst element of t h e buncher i s a uniform sec t ion of

disk-loaded waveguide with phase ve loc i ty equal to t h e ve loc i ty of t h e

in j ec t ed e l ec t rons v = .?c. This sec t ion i s about 30-in. long and

requi res about 2-kw peak dr ive power. The second element is a s i m i l a r

sec t ion wi th phase ve loc i ty v = .7c. This sect ion i s 6-in. long and

The buncher cons is t s of

P

P

'If simultaneous beams are not needed, a conventional gun can be mechanically in se r t ed by remote control .

- 15 -

requires 500-k~ peak drive power.

of the buncher as a 3=S0 bunch w i t h average velocity of 0 . 7 ~ .

t i o n of the electrons i n the second element of t h e buncher decrepses the

power required i n the f irst 10-ft accelerator section by a fac tor of two.

The f i r s t 10-ft accelerator section w i l l be designed t o require 10-to-12

Mw peak power f o r optimum capture and bunching i n order t o achieve excellent

klystron r p l i a b i l i t y .

The electrons leave the second element

The accelera-

- 16 -

1

V.

V. MICROWAVE CIRCUITS

A. GENERAL RF STUDIES 1. - Constant-Gradient Accelerator Structure

a. Coupler design

A brazed 2- f t sect ion corresponding t o the first nine cav i t i e s of the constant-gradient s t ruc ture became avai lable during t h i s period.

Using t h i s sect ion, the input coupler w a s matched. The correct dimen-

s ions are:

2b = 3.228 in .

Iris aperture = 1.160 in.

b. Group velocit,y and qual i ty f ac to r Q

Using the nine-cavity sect ion mentioned above, a measurement of t h e

average group ve loc i ty was made, yielding a value of vg/c = .0205 as

predicted by design.

y ie ld ing a Q of 11,500. This value appears somewhat low and may be

ascribed t o the f a c t t h a t the brazing of a t least one cavi ty i s def ic ien t .

These measurements w i l l be ve r i f i ed during the next quarter by using a

b e t t e r sec t ion .

The at tenuat ion constant turned out t o be ,126 nep/m,

c. Measurements of r/Q and space-harmonic amplitude

The tes ts concerning the measurement of the field-space-harmonic

amplitude of accelerator sect ions with d i sk thicknesses of .230 in. ,

-120 i n . and .060 in . as a function of group ve loc i ty have been completed.

A l l r e s u l t s appear i n Fig. 5a. the range of v /c between .005 and .022.

g v$, = 0 were obtained from theore t i ca l calculat ions. The three lower

poin ts correspond t o the thicknesses of .23O in . , .I20 in . and .060 in .

The fou r th point corresponds t o an i n f i n i t e l y th in disk. Also p lo t ted

on t h i s figure are experimental curves of the t o t a l value ( f o r a l l space

harmonics) of r/Q. This t o t a l value i s labeled as rdQ. Figure 5b gives the curves f o r the corrected values of

first space harmonic alone. From these

results it i s seen t h a t there i s a de f in i t e advantage i n going t o a disk

th inner than 0.230 in . , i f mechanical and thermal propert ies allow.

T h i s f igure gives experimental points i n

The four points shown fo r

r /Q corresponding t o the

This value is labeled as ro/Q.

- 17 -

V.

50

45

40

0

0

2nI3 MODE .64 -

1 1 1 I 1 -

-

-

0 0.005 0.010 0.015 0.020 0

.06 -

SQUARE EDGE DISK ('$ and rT&) Ea n (all other points hove beveled edges)

THEORETICAL VALUES

v - .62 I I g/c I I

FIG. 50--SPACE-HARMONIC AMPLITUDE AND TOTAL r/Q AS A FUNCTION OF NORMALIZED GROUP VELOCITY.

5

;0

i5

50

15

4 0

35

I I #

0.005 0.010 0.016 0.020 0.025

0.060"

,230"

1

t ro n Q (cm'

(For Fundamental Space Hormonic) vg/c-

35 FIG.5b--CORRECTED r/Q FOR SPACE HARMONIC AS A

FUNCTION OF NORMALIZED GROUP VELOCITY. (For various disk thicknesses: 0 . 2 3 0 , 0.120, and ,060)

- 18 -

V.

d. Constant-gradient f i e l d s tudies

The r e s u l t s given i n Fig. 3 of the previous S ta tus Report2 were found

t o be i n e r r o r .

sults.

caused by drawing a d i e l e c t r i c bead along i t s axis can be calculated as follows :

A mistake was made i n normalizing and p lo t t i ng the re-

The phase-shift var ia t ion across a matched accelerator section

d v flu v E* E2 cAV

€0) =-J?-=-- AV ( E - c o ) = - - ( 6 - t v u) v 4wt P 4

E l e c t ion g Q

where E i s the d i e l e c t r i c constant of the bead, AV is i t s volume,

P i s the power flow, W i s the energy stored, d i s the length of one

cavity, and t i s the length of a section. Thus, the curve obtained

from t h i s experiment i s not proportional t o r/Q(- E2/LCW) but t o E2/P.

By r ep lo t t i ng the curve and correct ing for the var ia t ion of the group

veloci ty along the s t ruc ture , it i s found tha t

From the design

A = l.g/meter

The agreement is fair. T h i s whole experiment w i l l be redone as soon

as a complete and matched constant-gradient sect ion becomes available.

2. Coupler-Asymmetry Measurement6

Previous t e s t s t o measure the a x i a l f ie ld asymmetry i n a coupler

caused by the opening of the coupling ir is were based on t h e measurement

2Status Report, M Report No. 280, Project M, Stanford University, Stanford, California, October 1961.

- 19 -

1

V.

of the phase shif t across the whole sect ion produced by a d i e l e c t r i c

bead drawn perpendicularly t o the coupler axis. lengthy and d i f f i c u l t t o perform.

appears much simpler,

coupler by inser t ing an e l e c t r i c probe in to the first disk hole.

suf f ic ien t t o introduce the probe verysl lght ly i n order t o pick up a s igna l , Although the in te rpre ta t ion of the curves is not as obvious as

f o r the previous method, the asymmetry or symmetry ( resu l t ing from B

corrected coupler) i s immediately apparent. O f course, t h i s method does

not permit sampling of the f ie ld at a radius greater than the disk hole,

but these measurements a re of no p rac t i ca l i n t e re s t since the electron

beam never sees those f i e l d s anyway.

These t e s t s were rather

A new method has been derived t h a t

"he pr inc ip le is t o sample the f i e l d inside the

It is

3. Using the r e s u l t s of Report No, 5105, P. N. Robson, Metropolitan-

Group-Velocity Measurements i n Cavity Tests

Vickers Co., Ltd. , quoted i n t h e previous Status R e ~ o r t , ~ and fur ther

approximations such as S t i r l i n g q s interpolat ion formula, it was found

tha t more accurate values of the group velocity can be obtained than

from the simple graphical method. By using s i x cav i t i e s and the re-

su l t i ng seven resonant frequencies on the w-p plot , the S t i r l i n g

interpolat ion formula gives group ve loc i t i e s about 3% higher than ob-

ta ined before.

4. Prebuncher Studies

The prebuncher mentioned i n the previous Status Report4 has under-

gone f i n a l assembly and i s now being t e s t ed before i n s t a l l a t i o n on the

Mark N. 5 . Properties of S-Band Waveguides

The choice of the cross sect ion f o r the 5O-ft waveguide joining

the klystron t o the accelerator sections i n the Project M accelerator

must be based on a var ie ty of cri teria suih as rf, mechanical, vacuum

propert ies and f i n a l cost .

propert ies were calculated f o r two types of rectangular S-band waveguide.

The r e s u l t s a re shown i n Table I. It seems t h a t the advantages gained

In order t o make t h i s choice, per t inent rf

3M-280, OP. c i t . , p. 19.

- 20 -

1

TABLE I

RF PROPERTIES OF STANDARD AM, ODD-SIZE S-BAND WAVEGUIDES

Standard S-Band Waveguide Odd-Size S-Band Waveguide

a = 2.840 i n . a = 3.900 in . b = 1.340 i n . b = 1.950 in .

f c = 2080 Mc/sec X = 15.32 c m a t 2856 Mc/sec X = 12.40 cm a t 2856 Mc/sec

f c = 1514 Mc/sec

g g = 1.395 x ohms Rs = 1.395 x lo-* ohms RS

Attenuat ion of TE,, Mode a t 2856 Mc/sec

a = 2.38 x nep/m

a = 2.067 x db/m

a = 6.30 x db/ft

a = 1.124 x nep/m

a = 9.763 x lo-’ db/m

a = 2.976 x lom3 db/ft

At tenuat ion of Higher Modes

a = 312 db/m

a = 338 db/m

a = 703 db/m TE1 1 a = 338 db/m

TEOL a = 610 db/m TEol

mll a = 703 db/m Y.1 TE,l.

0 Phase-Shift Change i n Degrees-per- C Change f o r 5O-ft Length

Bp = 1 . 2 3 O / O C 69 = 0.92O/’C

Average Heat Dissipat ion i n 50-f t Length

cal c a l - ’in, cm2 ’in. cm2

- =: 6 M W , ~ = 0.97 x = 6 MW, AP = 2.78 x

c a l ca l = 24 m, AP = 3.87 x 10” -

’in. cm2 ’in. cm2 ’ = 24 MW,AP = 11.1 x -

- 21 -

V.

from going t o a cross sec t ion wider than t h a t of t he standard S-band

guide a re not su f f i c i en t t o warrant i t s e x t r a cost . A more detailed

discussion of t h i s top ic w i l l be given i n a l a t e r report. 6. A ca lcu la t ion of the heat d i ss ipa ted i n a standard S-band wave-

The results are

Heat Dissipation i n S-Band Waveguide

guide w a s made t o design an opthum cooling system. shown i n Table 11.

7. In Stage I of the acce lera tor construction, each high-power klystron

Reflections i n 4-Way Fbwer S p l i t

w i l l feed four acce lera tor sect ions.

four ways i n the pa t te rn of a Christmas t r e e ( w i t h the k lys t ron on top)

by means of three o r two T I S (depending on whether the k lys t ron has a

s ingle o r double output) .

the power and phase var ia t ions caused i n any three sec t ions by the re- f l e c t i o n of power i n the fou r th sec t ion (due t o a sudden breakdown o r

gas bu r s t i n the sect ion) .

t h i s t i m e because the standing-wave r a t i o looking back i n t o the klystron

i s not known. However, it i s c e r t a i n t h a t t he power s p l i t s must be

achieved by means of magic T's capable of isolat i f ig the mismatch caused

by one sect ion breaking down.

gained from using magic T ' s .

all four waveguide lengths from klys t ron t o acce lera tor must be equal,

it w i l l be possible t o insure t h i s equal i ty upon i n s t a l l a t i o n by de-

tuning the first cavi ty of t he acce lera tor sec t ions and ad jus t ing the

waveguide runs u n t i l no power appears i n the four th arm of each magic T. Alternatively, ins tead of detuning t h e first cavity, another method

would cons is t of sending a frequency f o r which the acce lera tor input

iris a c t s as a perfect shor t .

The power s p l i t w i l l be achieved

A ca lcu la t ion has been ca r r i ed out t o pred ic t

This ca lcu la t ion cannot be completed a t

A n addi t iona l advantage can a l s o be

Since i n the Christmas t r e e arrangement

8. Pumpout Work

Work has s t a r t e d on a pumpout i n the form of an H-plane T-junction

w i t h a band-elimination f i l t e r cons is t ing of two posts placed so as

t o present zero impedance t o the pumpout arm. Two models have been

constructed and high-power tests w i l l be made i n the next quarter .

9. Waveguide-Vacuum Valve

Work has a l s o s t a r t e d on a waveguide-vacuum valve. The present

model i s being t e s t e d f o r rf proper t ies t o a sce r t a in whether it can be

matched without using i r i s e s . Results appear encouraging.

- 22 -

v.

TABLE I1 PWER DISSIPATION I N RECTANGULAR S-BAND WAVEGUIDE FOR THE TE,, MODE

a = 2.840 in . = 7.22 cm

b = 1.340 i n . = 3.41 cm A, = 10.5 cm

P and Px a r e the average powers diss ipated i n t he t o p or bottom Y

and s ide w a l l s respectively.

where 7 =E, Rs i s t h e surface r e s i s t i v i t y , X g i s the guide wavelength

and X i s the free-space wavelength.

X, = 10.5 cm, these expressions y i e l d For standard S-band guide, and

P = K pX = K (1 - 0.116 sin2 y) Y

An approximate p lo t is shown below. PY/K Px/K

The t o t a l powers P and P a r e obtained by integrat ion. X Y

2 a R s Eo2 b R s Eo2

2 7 1 'y t o t a l

- - - - 4 v2 'x t o t a l

za3 The r a t i o i s - = 2 f o r standard S-band guide a t

A .'b A, = 10.5 cm.

The power d iss ipa t ion appears t o be p r a c t i c a l l y constant around t h e guide.

I t can e a s i l y be shown t h a t f o r any Tno mode, t h e above r a t i o i s

px 2a3 - =

2 2 P n lob Y

- 23 -

v.

B. DRIVE SYSTEM

1. Design Studies

More work was done during the pas t period t o examine a l te rna t ive

solutions t o the dr ive system f o r the accelerator . The design using a

coax drive l i n e i s s t i l l preferred a t t h i s time. However, a proposal

has been made t o t r a n s m i t the master s ignal a t a lower frequency (119 Mc/sec)

a t which the loss i s small enough t o allow elimination of a l l s e r i e s

boosters. This proposal, however, has the disadvantage t h a t frequency

mul t ip l ie rs must be incorporated ahead of each sub-booster. Although

much progress has been made i n designing frequency mul t ip l ie rs with

varactor diodes, it i s not cer ta in a t t h i s point whether the required

phase s t a b i l i t y can be obtained with these devices.

w i l l continue throughout the next two quarters.

Work on t h i s design

2. Mark IV Drive System

The rf system f o r the Mark IV w a s completed during t h i s quarter and

has been i n operation f o r about one month.

500 w a t a pulse length of about 7 psec i s avai lable a t each klystron.

An ins t ruc t ion manual of the system for the operating and maintenance

personnel i s being prepared.

A peak power of approximately

3. Radiofrequency Driver

The rf dr iver b u i l t by Granger Associates of Palo Alto was accepted

during the pas t period.

of the dr iver appeared sa t i s fac tory , as seen from Table 111.

After a number of correct ive measures, operation

4. Frequency and Phase Measurements

The frequency-stabil i ty measurement of the Granger dr iver was done

by observing the beat between i t s cw output and m o t h e r s tab le source

(a Hewlett-Fackard t r ans fe r o s c i l l a t o r )

by l e s s than 2 kc during a few milliseconds.

s t a b i l i t y of both sources.

"he "period" of the beat var ies

This number includes the

In order t o perform the phase-s tabi l i ty measurements, work is being

done on two d i f f e ren t methods. The first w a s suggested a t Varian Asso-

c ia tes . It is based on comparing the input and output pulses from the

las t amplifier stage of the dr iver with a l o c a l o s c i l l a t o r (off by about

30 Mc/sec), mixing the s ignals , picking out the 30 Mc beat , amplifying

and clipping the s ignals and f i n a l l y feeding them in to a phase detector

operating a t i . f .

be adapted t o pulsed operation.

This scheme has worked very w e l l a t cw but must now

- 24 -

v.

~

Spurious frequencies above 1000 Mc/sec i n the output of t he system, a t l e a s t

Pulse specif icat ions

Length

Rise time

Time j i t t e r re fe r red t o main sync. t r i g g e r

Pulse-height deviation from f l a tnes s

TABLE: 111

GRANGER DRIVER REQUIRED SPECIFICATIONS AND MEASURED CHARACTERISTICS

Required Character is t ic s Measured

IMain rf power output 5000 w 5400 w

Powe r - amplitude stab i l i t y (pulse t o pulse) I

2857.5 Mc/sec 2857.53 Mc/sec Center frequency

Frequency tuning * 2 Mc/sec - 2.3 Mc/sec -t. 1.6 Mc/sec

< 2kc during a t i m e of the order of m i l l i - seconds (see text)

t Short-term frequency

s t a b i l i t y of cw output

-~ ~~

Rate of change of phase c Long-term frequency st a b i l i t y

s h i f t < 2O/3 psec (see text)

0.38 kc during 40 min 5 5 kc(for 1 h r )

Nothing v i s ib l e betweei 2600 and 2950 Mc/sec, 30 db down

50 db down

7 psec a t 60 pps 6 . 1 psec at 360 pps

- 0.2 psec

Not m e asurtzble with su f f i c i en t accuracy because of main t r igge r j i t t e r

3 vsec

0.2 psec max

0.02 psec

+_ 0.25$ over 6 psec 5 1% over 3 psec

- 25 -

v.

The other method has been proposed by the Rantec Corporation of

Calabasas, California. 'It uses a bridge w i t h four magic TIS. A cw

reference s ignal i s fed in to one of the arms of the bridge and the pulsed

s ignal comes in to the other arm. The bridge i s arranged i n such a way

tha t i t s outputs are proportional t o the sine and cosine of the phase

modulation i n the pulsed signal.

played on a scope o r fed in to a r a t i o meter giving the tangent of the

phase modulation.

Hence, these outputs can e i t h e r be dis-

Tests on the Rantec phase discriminator have been

s ta r ted and w i l l be continued during the next period.

5. Sub-Boosters

Following some d i f f i c u l t i e s w i t h their filaments,

klystrons on loan from the CFTH Company of France were

Paris and checked. According t o the manufacturer, the

caused by the filaments disappears completely when the

the TH-2101 flown back t o

beam modulation

tubes are driven

in to saturat ion.

t e s t s w i l l be performed.

The tubes a re now back i n t h i s laboratory and fu r the r

C. PHASING SYSTESI

1.

This method of phasing long l i n e a r accelerators w a s formerly ca l led

Current Variation Detection Technique of Phasing

the "beam energy maximization" technique.

i n analyzed beam current t h a t is detected and not the change i n beam

energy, t h i s more appropriate t i t l e has been adopted.

However, since it i s the change

A detailed analysis of t h i s technique has been carried out after

s implif icat ion of the problem by approximating the energy spectrum by

a t r i ang le ,

f o r a number of d i f fe ren t spectra has been considered.

fo r the order of magnitude of the change i n current and the required

sens i t fvf ty of the detector have been calculated using the ex i s t ing

Project M specif icat ions.

details of these calculat ions,

The e f f ec t of t he eneru-spectrum shape on analyzed Current

Numerical examples

A separate report is being prepared giving

2. Mark I11 Experiments

An attempt was made t o simulate the "current var ia t ion detection"

technique of phasing on the Mark 111 accelerator.

phase s h i f t e r was ins t a l l ed on the dr ive of the last Mark I11 klystron,

and i ts dr ive power was reduced t o a l e v e l yielding an output power of

A remotely-controlled

- 26 -

about 300-kw peak.

the t o t a l beam of about 1/2$ and thereby simulates the e f f ec t of one

klystron being phased at f u l l power on the 2-mile accelerator.

phase of t h i s under-driven kiystron was modula.ted by hand, the dr ive

was turned on and off and the e f f ec t was observed on the analyzed current

of the accelerator. Unfortunately, the beam was not s tab le enough, and

other var ia t ions swamped out t he varying contribution of t he las t klystron.

It i s a l so possible t h a t the e f f ec t was not seen because at t h i s very low power the corresponding accelerator sect ion was too cold t o operate i n

synchronism* Also, even though the t o t a l beam current w a s reduced below

5 ma, it i s possible t h a t t h i s last sect ion was operating at considerable

beam loading; therefore, i ts contribution w a s too s m a l l t o be seen.

Another attempt t o eliminate these d i f f i c u l t i e s and tes t t h i s method of phasing w i l l soon be made. A s i m i l a r experiment i s being planned on t h e

Mark IV with a separate cavi ty i n l i n e w i t h t he beam.

This power corresponds t o an energy contribution t o

While the

3. Induction Method

Phasing of a Non-synchronous Accelerator Section by the Beam-

M Report No. 288, carrying t h i s t i t l e , w a s published during the pas t 5 quarter .

4. This method makes use of t h e s igna l induced by the beam i n a separate

Phasing Method using a Separate Cavity

cavi ty i n l i n e with the accelerator sect ion and connected t o it through a

cutoff waveguide. Th i s scheme w a s o r ig ina l ly proposed by K. B. Mallory

i n 1957. 5 . Redesign of Phase Detector

The phase detector previously used f o r the beam-induction method

of phasing i s present ly being redesigned.

6 , Fer r i t e Components

The f a c i l i t y with which fe r r i te phase shifters and a t tenuators can

be remotely controlled, and t h e i r usually small s ize , have l ed t o t h e i r

consideration f o r use i n the rf system of Project M. In connection with

the preparation of t h e specif icat ions fo r these phase s h i f t e r s , i so l a to r s ,

and at tenuators , a number of de ta i led microwave measurements have been

undertaken on avai lable components. Effort so far has been d i rec ted

5G. A. Loew, "Phasing of a Nonsynchronous Accelerator Section by t h e Beam-Induction Method," M Report No. 288, Project M, Stanford University, Stanford, California, November 1961. - 27 -

1 .

towards the phase s h i f t e r , but measurements on the a t tenuators and iso- l a t o r s are planned.

vironmental and operating conditions i s of considerable importance.

The s t a b i l i t y of the components under varying en-

Typical r e s u l t s f o r one type of e lectronical ly-control led ferr i te

phase shif ter are shown i n Fig. 6, which gives the var ia t ion i n phase s h i f t as a function of temperature f o r a given value of control current .

The change i n inser t ion loss as a function of control current f o r three temperatures is shown i n Fig. 7. Considerable var ia t ions i n in se r t ion

l o s s as a function of power l e v e l have a l so been observed.

detailed study of t h i s phenomenon i s planned, together w i t h an inves t i -

gation of the W s t e r e s i s e f f e c t s i n f e r r i t e components of t h i s type.

A more

Present indicat ions show t h a t considerable development work is s t i l l

required on these components before they w i l l meet t he proposed speci-

f ica t ions .

20(

-i = 60

4 = 20

-

I I I I I 1 80 90 100 110 120

To Farenheit 130 140

FIG. 6 - -~hase s h i f t e r B: phase s h i f t ( c p ) vs ambient temperature a t various currents (i ). m a

- 29 -

V.

- I I I I I I I I 0 20 40 60 a0 100 120 140 160

3

6

2

1 ma i

30 -

VI.

VI. KLYSTRON STUDIES

During the last quarter t he Klystron Group has continued i t s research

on permanent-magnet-focused klystrons, l i f e t e s t i n g of ex i s t ing klystron

s t ruc tures , and maintenance of an adequate stock of tubes f o r accelerator

and component s tudies and has begun an analysis of the number of tubes

needed between now and beam-on time of the Project M accelerator . In

addition, the present 'subcontracts are being carefu l ly monitored and plans

a re being l a i d f o r procurement of the klystrons needed f o r t he accelerator

ope rat ion.

A. TUBE COMPLEMENT ADD RZTQRMANCE

The complement of tubes on hand remairis esseiitittiLji conslant; t ha t

is, t h e tubes t h a t have f a i l e d on l i f e t e s t a re being replaced a t a regular r a t e .

W e are a t present bui lding two kinds of tubes, the "long" tube and

the ' 'short" tube. The long tube i s iden t i ca l i n e l e c t r i c a l cha rac t e r i s t i c s

t o those t h a t have been b u i l t f o r t he las t two years . We are now using

the long tube on l i f e t e s t s .

M Report No. 2 8 0 ~ ) spec i f i ca l ly f o r use w i t h permanent magnet.

reasons t h a t are not ye t c lear , t he gain and ef f ic iency of the short

tube a re not as high as expected. Specif ical ly , the computations in-

dicated t h a t the short-tube gain might decrease by 3 db over the long-

tube gain, but i n prac t ice the decrease i n gain i s c lose r t o 6 o r 8 db.

Similarly, the change i n length i n the d r i f t tubes was expected t o have

l i t t l e o r no e f f e c t on t h e eff ic iency. In pract ice , t he shor t tubes have

i n f a c t shown an e f f ic iency of approximately 32$,as against 38$ f o r the

long tubes.

The short tube has been designed (see

For

A serious study of t h i s decrease i n gain and ef f ic iency i s now

being undertaken, and some spec ia l tubes w i l l be b u i l t t o determine what

remedial measures have t o be taken.

We have a l so begun the production of p a r t s w i t h which t o bu i ld

tubes t h a t w i l l conform t o the general out l ine of t h e klystron decided

upon i n February, and which appeared i n the quar te r ly s t a t u s report of

%ta tus Report, M Report No. 280, Project M, Stanford University, Stanford, California, October 1961.

- 31 -

April- 1961.7 and the f i r s t , tubes of t h i s var ie ty should be available during the next

quarter f o r i n i t i a l t e s t s .

The program of construction of these tubes i s wel l under way,

B o RESEARCH AND DEVELOFIENT SUBCONTRACTS

At, the present time both subcontractors (Sperry Gyroscope and RCA)

a re behind schedule.

the end of February. These w i l l be permanent-magnet-focused tubes. I n

addition, Sperry w i l l de l iver two electromagnet-focused tubes f o r our

evaluation of t h e i r bes t e l e c t r i c a l design,

Sperry i s now planning t o del iver three tubes by

The RCA subcontract d id not contemplate the del.ivery of any tubes

before January 1962. observe one of t h e i r tubes i n operation, but during the t e s t s of t h a t

tube an output window f a i l e d by puncturing and cracking. When the load

was removed, the tube went down t o air and w a s scheduled f o r Immediate

repairs . I n general, the RCA tubes follow very closely the e l e c t r i c a l

design of the Stanford tubes.

performance, although ce r t a in measurement d i f f i c u l t i e s make an accurate

evaluation of the t e s t r e s u l t s d i f f i c u l t . The mechanical design of the

RCA tube i s qui te novel, but has ye t t o be proven out.

During our last. v i s ik s at, RCA we were able t o

The f i r s t t e s t s indicate very similar

C. NEW FACILITIES

The lack of gases and chemical cleaning f a c i l f t d e s a re s t i l l

hampering the operations of the tube shop. The t h i r d modulator f o r

the klystron development program i s not yet i n operatfon. Addi-

t i o n a l t e s t s on all-metal high-power loads have not been completed

because of various mechanical d i f f icu l t . i es t h a t

7Status Report, M Report No. 260, Project M. StJanford University, Stanford, California, April 1961.

- 32 -

V I .

were encountered i n the fabr ica t ion of these loads, We are a l so i n t he

process of revising some of our pump systems on the load.

explained below, a l l the tubes t h a t we have had on l i f e t e s t s have f a i l e d

eventually from window punctures o r window cracking.

a l l tubes t h a t f a i l e d on l i f e t es t had bad windows at the t i m e of f a i lu re .

It has been observed t h a t the ion-type pumps on the load system are apt t o s t a l l during t e s t s . Accordingly, some new ion-type pumps are being

procured i n an attempt t o remedy t h i s s i tua t ion . Diffusion-pump systems

are also being b u i l t .

A s w i l l be

That i s t o say,

D. LIFE TESTS A t present we have one modulator operating 24 hours a day, 7 days

a week.

and equipment, we accumulate approximately 500 t o 600 hours operating

t i m e per month. In general, t h e l i f e t e s t i s being run a t approximately

one-half of ra ted m a x i m u m power of the klystrons:

peak, 10-to-12 kw average, 360 pps, 3 psec pulses. Under these conditions

we have had one tube operating f o r 600 hours and several tubes exhibi t ing

f a i l u r e s a t between 50 and 200 hours. It i s d i f f i c u l t t o determine at

the present t i m e i f the failures are due e n t i r e l y t o t h e tube o r are due

i n pa r t t o t h e t e s t equipment i t se l f . As mentioned above, it i s r a the r

frequent for t h e load vacuum t o de te r iora te rapidly t o the point where

ionic pumps s ta l l . for these pumps, it was not p r a c t i c a l t o make immediate changes i n the

c i r c u i t r y t o introduce inter locks between the load vacuum and the modu-

l a t o r operation. This has been accomplished now, but t h e in te r locks

have not been i n operation long enough t o permit evaluation of the new

operating conditions. In several cases we have found a punctured tube-

cathode bushing, but it i s probable t h a t the bushing f a i l u r e followed

the f a i l u r e of the window and the consequent de te r iora t ion of the vacuum

on the tube s ide.

Under these conditions, counting breakdowns and change of tube

between 10 and 12 Mw

Because of t he design of some of t he power supplies

I n most, i f not i n a l l , cases of window f a i l u r e s there seems t o be

a simultaneous loss of vacuum i n the load.

instrumentation i s not good enough t o determine i f the loss of vacuum

i n the load precedes the window f a i l u r e o r i s a resu l t of it. In t h e

fu ture we hope t o be able t o devise a system by which w e can determine

A t the present time the

- 33 -

1

'VI.

whether the load vacuum deter iora tes f o r other reasons, o r i f an e lec-

t ron ic a c t i v i t y at the window surface produces a l o c a l de t e r io ra t ion of the vacuum which then enhances the chances of window puncture, breakdown

and cracking.

It must be s t a t ed at t h i s point %hat we have a l so had window failures

on the bery l l ia -d isk windows t h a t have been used i n the last, t h ree tubes

operated under l i f e - t e s t conditions.

E. EXPERDENT&TUBES

A t the present time we a re running t e s t a on experimental permanent-

To date we have t e s t ed two tubes i n one permanent magnet-focused tubes.

magnet. The first tube t e s t e d w i t h a permanent magnet had first been

t e s t e d on the electromagnet and operated with an e f f ic iency of approxi-

mately 30q&* of t h i s tube dropped t o between 10 and 12$

ef f ic iency w a s caused by an inadequate shielding of the s t r ay f ie ld from

the permanent magnet i n the cathode region, The addi t iona l work done

on shielding i n the gun region of the klystron resu l ted i n much more

sa t i s f ac to ry r e s u l t s f o r the second tube t e s t ed on the permanent magnet.

In t h i s case, the eff ic iency was about 32$ with electromagnet and about

22% on permanent magnet. A r a the r s t a r t l i n g f a c t about t h i s tube, how-

ever, i s t h a t w i t h the permanent magnet t he gain i s higher and t h e

maximum e f f ic iency OCCUTS at a dr ive much Power than that. whfch we had

measured with the electromagnet, I n other words, at very low d r ives t h e

permanent-magnet tube appears t o behave b e t t e r than what we had observed

with electromagnets, although w e had attempted t o dupl icate the f i e l d

of the permanent magnet as closely as possible w i t h electromagne.ts.

t he o ther hand, the permanent magnet would not permit the sa tu ra t ion

eff ic iency t h a t was observed with the electromagnet under supposedly t h e

same magnetic-field conditions, There are several possible explanations

for these differences i n behavior, and these w i l l be inms t fga ted during

the next quarters.

Once i n s t a l l e d i n the permanent magnet, the e f f fc iency

This d r a s t i c decrease i n

On

F. PLANNING THE KLYSTRON PROCURmENT It is our hope t h a t a production contract f o r the procurement of

klystrons f o r use on t e s t stands and on the two-mile acce lera tor can be

VI "

signed during the calendar year 1962. plans on the numbers of tubes needed and the approximate schedules a t

which these tubes must be procured.

plement of tubes needed f o r the accelerator (240 plus about 10% spares),

a large number of klystrons will be needed f o r t e s t s of the tubes them-

selves and fo r other components.

Accordingly, we have begun making

I n addition t o the i n i t i a l com-

If the present estimate of 2000-hours life for t he klystrons operat-

ing on the accelerator proves valid, the totalpumber of tube replace-

ments per month w i l l be between 80 and 90. Plans w i l l soon be made t o

prepare for the acceptance o r re jec t ion of tubes t o f u l f i l l a l l of these

requirements e

G. KLYSTRONS ON MARK Tv

Two klystron tubes are now being used on the Mark N accelerator .

The power output from these tubes i s approximately one-half of what we

had measured under t e s t conditions.

not c lear , but appears t o be caused by inadequate instrumentation,

An attempt t o reconcile the da ta i s being undertaken w i t h the help of

the klystron group.

The reason for t h i s discrepancy i s

- 35 -

V I I .

V I I . HIGH-POWER KLYSTRON WINDOWS

A. WINDOW-LIFE TEST STAND

The l i fe - tes t un i t has been operated about 250 hours during the

l a s t quarter, w i t h s i x windows under t e s t . Most of the time it was below

6 Mw, l imited by breakdown i n the pressurized section between the tube

and the f irst window. T h i s has been traced t o moisture i n the freon

and t o a mismatch a t the f i r s t window.

a t 9 Mw but it has been' unreliable.

but does not leak, a t the same sect ion where a window was damaged last quarter.

Some operation has been obtained

One more window has been punctured,

Hours on these two windows were 65 and 120 respectively.

The new trigger-generator units arr ived from Ling during the quarter,

and the operation of the modulator has, i n general, been sa t i s f ac to ry

since t h e i r i n s t a l l a t ion . One of %he Litton type-L 3302 klystrons had

t o be removed because of arcing at high-power levels . The second tube

i s now i n use.

of the Mark V klystron on t h i s system. T h i s w i l l enable us t o t e s t

windows above the 10-Mw l i m i t s e t by the Litton tube. We are s t i l l awaiting a r r i v a l of addi t ional power supplies so that the number of

windows under t e s t can be increased t o twelve.

A new power combiner i s under construction t o allow use

B e RECIRCULATOR WINDOW TESTS

The following tests have been made on t h i s equipment during the

past quarter.

1. Half-Wave Disks

Two more half-wave disks have been tes ted . The first d i sk (No. 4) w a s i n a s t ruc ture s l i g h t l y modified from Fig. 6(b) of the last Status

Report.8 The 2.875-in. dim. region w a s lengthened t o remove the window

farther from the tapered region.

surface i n t h i s geometry, but developed several holes on the circum-

ference due t o poor contact with the metal walls. t e s t e d i n the o r ig ina l geometry; the failure w a s much l i k e t h a t shown i n

Fig. 7 ( I ) i n the last status Report.g

The window did not break down on the

This d i sk f a i l e d when re-

"he second disk (No. 6) was tea ted

'Status Report, M Report No., 280, Project M, Stanford University, Stanford, California, October 1961, p., 29.

'M-280, OP. c i t . , p a 30. - 36 -

VII.

i n the o r ig ina l s t ructure and f a i l e d on the generator side with the

pa t te rn shown i n Fig. 8. quickly s t ab i l i zed and operated normally.

have f a i l ed on the source side and two have f a i l e d on t h e load.

When reversed, it showed some breakdown b u t

So far, three of these d isks

These th ick disks are the only types on which we have obtained

consis tent surface punctures. In a l l cases the a c t i v i t y t h a t was v i s i b l e

w a s confined t o the region of f a i lu re . So Tar, the side on which puncture

occurs seems a matter of chance.

cussed above) it seems as i f the geometry i n the neighborhood of the d isk

i s important. The "clean up"

of a Stanford and a Sperry window (see below) lends support t o t h e idea

t h a t f a i l l x e r e s u l t s from the r i g h t circumstances and i s immediate, and

t h a t gradual de te r iora t ion does not occur.

2. Sperry Thick-Disk Windows

These were similar i n construction t o the J-type,"

On the bas i s of one t e s t (No. 4, d i s -

Further t e s t s a re planned t o check t h i s .

except t h a t

the d i sk of AD993 i s ,640-in. t h i ck instead of . l25 in . The t r a n s i t i o n

from cyl indr ica l t o rectangular waveguide i s a l so much l e s s abrupt.

Three of these windows were tes ted . One f a i l e d a t less than 1 Mw,

apparently due t o poor construction at the metal-to-ceramic seal s ince

breakdown occurred i n t h i s region.

time a t approximately 27 Mw when rf breakdown s t a r t ed .

w a s no v i s ib l e evidence of trouble, the l e v e l of breakdown slowly de-

creased u n t i l it s t ab i l i zed a t 8 Mw. T h i s cycle w a s repeated severa l

t i m e s . The t h i r d window had an ear ly period of violent arcing during

which some punctures occurred (as i n the half-wave windows). It then

s t ab i l i zed and operated normally.

3. One-Sixteenth-Inch Disks

One addi t ional 1/16-in. d i sk of Coors AD 96 w a s t es ted .

The second window ran f o r a short

Although the re

It operated

normally at the highest power avai lable .

Mark I11 accelerator by operation w i t h sudden turn-on a t high power and

poor vacuum were a l so unsuccessful.

Attempts t o simulate damage on tiie

"Status Report, M Report No. 272, Project M, Stanford University, Stanford, California, July 1961, p. 16.

- 3 7 -

V I 1

FIG. 8--Half-wave disk No. 6.

FIG. g--Failure of b e r y l l i a window. - 3 s -

V I I .

4. Dry Calorimeter

The r ing was used b r i e f l y f o r t e s t s on 8 dry calorimetric type of

power meter.

5 . Photographic Work

A considerable e f f o r t was made t o improve the photography of events

i n the ring.

mation of holes w i t h "stars" occurring on the operating window.

was unsucceesful with the present equipment. We are invest igat ing equip-

ment t h a t w i l l be sui table .

camera t o take sequential p ic tures of breakdown.

In par t icular , an attempt was made t o cor re la te the fo r -

This

We a l so hope t o be able t o use an ex i s t ing

6 . Increased Ring Power

Some of the equipment t o increase r ing power i s now complete. The

remainder should be here ear ly next quarter.

Li t ton type-L 3302 on t h i s un i t .

We now plan t o use a

c. OTHER WINDOW WORK 1. Resonant Cavity Tests

A s e r i e s of tests was run w i t h t h i s apparatus using the Raytheon

5936 magnetron as a driver.

much t o be desired, these t e s t s showed tha t the loading i n the cavi ty

w a s very heavy.

dr iver .

i n a very strange manner and is not understood.

occurred on the surface of the d i sk during these t e s t s .

the cavi ty behaved i n a normal manner. We are now making arrangements

t o dr ive the cavi ty from a ~ ~ - 8 7 klystron using a s m a l l modulator bor-

rowed from the Hansen Labs.

2. X-Band Fower

We have recently detected X-band frequencies i n both the resonant

Although the s t a b i l i t y of t he system l e f t

Tests were a l so m a d e using the more stable VA-87 r i n g

The loading of the cavi ty as a function of power input behaved

A very br ight discharge

Without the disk,

cavi ty and the resonant ring.

whether t h i s power w a s from the dr iving tube o r being generated i n the

t e s t s t ructure . The use of a General Elec t r ic Company low-pass f i l t e r

on the ring has reduced the amplitude by more than 20 db.

invest igat ing i f the remaining X-band power maJr be due t o nonlinearity of

window s t ruc tures .

In both cases there was not c l ea r evidence

We are now

- 39 -

V I I .

4

3. Mark I11 Window Fai lures

Another window recently failed on t h i s accelerator. This makes

three since last July, in contrast with the former rate of 6.6 per month. We are s t i l l unable to duplicate these r e s u l t s on r ing t e a t s .

4. Beryl l ia Windows

I'wwo hcqyl l ia disks have f a i l e d on Mark V klyatrons. These were at

l eve ls of about 6-kw average and 6-m peak powers.

by vacuum pump failure, so it is not known i f , h i g h pressure m a y have caused these. In the one window t h a t has been examined, there w a s a

large crack plus punctures ident ica l i n appearance t o those i n alumina

disks (see Fig. 9). mounted i n the s t ruc ture shown i n Fig. 10.

Both were accompanied

These were 2.5 in . i n d i m and-200 in. thick,

-

FIG8 lO--Beryllia window assembly.

VI11 *

V:I:Il. MODULATOR STUDIES

A. PROJECT DEVELOFMENT ACTTVITIES 1. Igni t ron Studies During the h s t Quarter

During the past quarter we have t e s t ed two versions of t h e 2-5233

igni t rons, one with and one wlthout a splash ba f f l e .

concluded the s e r i e s of t e s t s on these tubes, we have found t h a t t h e

2-5233 w i t h baffle does indeed perform w e l l as a pulse modulator up t o

120 kw OP average power. This result, indicates %hat, our previous un- sa t i s fac tory tes ts with t h i s tube were the resuit, of a faulty tube r a t h e r

than a basic design e r ro r .

While we have not

During the past quarter w e have also shown t h a t t he 2-5234 with

splash ba f f l e operates very s a t i s f a c t o r i l y a t a 60-cycle p r f on the

Mark N i n s t a l l a t ion , where the tube is switching two networks i n

p a r a l l e l and passing 8,0o0-amp9 3-psec pulses.

Complete details of the test r e s u l t s on t h e 2-5233 and 2-5234 w i l l

be compiled and published as soon as possible.

I n addition t o the s tud ies mentioned above, w e a re cur ren t ly t es t -

ing a new sample of an ign i t ron constructed In accordance with our

Drawing 504-911..11 For t e s t purposes t h i s tube i s being cooled i n a

constant-temperature o i l bath, r a the r than a water jacket.

2. ApplicatIon of Sol id-s ta te Diodes

During the past quarter w e have encountered a s e r i e s of failures

In of so l id-s ta te u n i t s used f o r c l ipper and hold-off diode service,

par t icu lar , we are unable t o t r ace the hold-off diode f a i l u r e t o any c i r c u i t cause, We have conducted an extensive s e r i e s of t es t s on our

c i r c u i t r y i n cooperation with Westinghouse E lec t r i c Company, which

furnished the diodes; it concurs with us that, t he failure i s due t o the

diode i t s e l f , ra ther than the c i r c u i t , The Westinghouse Company I s

present ly attempting t o f ind a solution f o r t h i s t rouble .

3 . Tests conducted on the 5,OOO-amp, 2-kv switch during t h e pas t

Invest igat ion of Solid-State Switches -

period have no t been very promising. The unit; furnished t o us by

"The tube currently being t e s t e d i s the shol-tes version of the two, and we expect t o know i t s behavior by approximately December 27.

- 41. -

V T I I "

Shockley Transistor Corporation f a i l e d a f t e r a few pulses at low currents .

This phase of the program i s being deferred u n t i l a l a t e r date ,

4, In order t o accommodate some high-power rf t e s t i n g t h a t i s required

Additional Act iv i t ies of the Modulator Development Group

by the Accelerator Structures and Vacuum Groups, t h i s department i s

preparing t o move OUT" exis t ing high-powey t e s t laboratory equipment t o

another area s t a r t i n g about December 27.

order a new 120-kw power supply t o replace our present un i t and a re

making necessary arrangements t o tu rn over enough equipment t o flrrnfsh

a complete working modulator t o tohe Accelerator Structures Group.

We have accordfn@y placed on

- 42 -

IX.

IX. VACUUM SYSTEM

A. MARK IV CONVERSION The Mark IV vacuum system was held under vacuum f o r the en t i r e

quarter at 3 x Radiofrequency power was s ta r ted during t h i s

time andalso some outgassing of the klystron area system. After the rf

power w a s run through the klystron waveguide, tha t vacuum leve l reached

7 x not enough t o outgas t h e tubes completely.

is presently holding at 3 x lom7 t o r r .

outgas the accelerator tubes and reduce the vacuum level .

tubes have a very large surface area and require a large amount of rf

processing t o outgas them.

t o r r .

t o r r . The accelerator tubes saw a small amount of rf power but The accelerator-tube vacuum

Further rf-power processing should

The accelerator

B. Fl3ASmILITY STUDIES

Another vacuum equipment mandacturers' inspection t r i p w a s made.

The manufacturers were acquainted with the vacuum requirements of the

project and a means of further communication w a s established.

C. PROBLEM STUDIES

1. Sixty f't of waveguidewere evacuated and t he pumping speed at 20,

40 and 60 f t measured.

and a check of t h e data w i l l be made.

Further outgassing of the waveguide is necessary

2. The equipment f o r outgassing studies w a s fabricated and run. Eigh t different cleaning procedures were checked f o r their outgassing

e f fec t on 304 s ta in less s t ee l .

charac te r i s t ics of different materials.

Next we w i l l check the outgassing

3. The automatic bakeable high-vacuum valve has been fabricated

and is ready fo r tes t ing .

ing torque and found t o be as follows:

The gasket sea ls have been checked f o r seal-

Because of the d i

Indium

Gold

Aluminum

Copper

advantages en

3 ft-lbs

5 f t - l b s

3 ft-lbS

7 f t - l b s

ountered i n the use of In, Ag and Cu,

we are using Al gaskets f o r the t e s t valve.

- 43 -

IX.

4. Molecular s ieve t r a p s a re being fabr ica ted and checked so

that the t r a p dimensions and operat ing cha rac t e r i s t i c s can be determined.

5. The new meta l l ic gasket and flange system was operated satis- f a c t o r i l y i n 1, 2, 3 and 4-in. s izes , but d id not work i n the 6-in. size.

The system is being redesigned and reworked f o r fu r the r tes t ing .

6 . A t e s t pump stand i s being fabr ica ted t o start the var ious

vacuum-equipment evaluations needed p r i o r t o se lec t ing equipment f o r use

on Project M.

D. CONCLUSIONS The Mark IV vacuum system operated successfully f o r t h e e n t i r e quar-

t e r .

fu r the r processing i s necessary.

Radiofrequency power processing improved the vacuum leve l , bu t

"he research s tud ie s necessary f o r determining the outgassing of

mater ia ls , t h e valve, f lange and pumping systems t o be used on the

pro jec t a r e progressing s a t i s f a c t o r i l y .

A study t o ready the design of the molecular sieve trap f o r produc-

t i o n i s underway and should provide usefu l data i n t r a p e f f i c i enc ie s .

The program t o provide information i n t h e evaluation of ava i lab le

vacuum equipment has been s t a r t ed .

x.

X. SUPPORT AND AJJGNMENT

A. SITE EARTH-MOVEMENT STUDIES

The r e su l t s of the several elevation surveys t o date a re inconclusive.

The apparent var ia t ionsin t h e elevation of cer ta in points of the survey

are possibly w i t h i n t h e accuracy o f the surveying technique. Additional

surveys are t o be performed. Some new surveys w i l l cover the e n t i r e

s i t e ; others w i l l be l imited t o the region of indicated uncertainty.

A permanent three-legged hydraulic tilt meter has been i n s t a l l e d

a t the s i t e i n the v i c in i ty o f the apparent var ia t ions i n elevation.

Some d i f f i c u l t y has been experienced i n correlat ing the observations of

the tilt meter t o those of the survey.

crepancies w i l l be resolved a s more observations a re made.

It is hoped t h a t these d i s -

The new schedule f o r the s t a r t i n g of the t r iangulat ion and tri-

l a t e ra t ion surveys i s set f o r January.

survey have been completed.

t o a r r ive soon.

The permanent monuments for t h i s

The last of the required equipment i s due

B, SUPPORT

Investigation of t h e poss ib i l i t y of the use of a fo r ty - f t , simply- supported accelerator substructure has continued.

been given t o the e f f ec t s o f transverse forces on such a s t ruc ture .

Forces on the waveguides, due t o d i f f e r e n t i a l motion of the klystrons

r e l a t ive t o the accelerator substructure, have been estimated. Fr ic t ion-

l e s s couplings f o r attaching adjacent, substructures t o allow f o r thermal

expansion have been proposed. Aluminum, s t a in l e s s s t e e l and mild s t e e l

have been considered as materials from which the substructure might be

fabricated. Financially, aluminum and s t a in l e s s s t e e l are nominally

equivalent. The cost of the mild-steel substructure would be much l e s s .

However, the magnetic propert ies of the mild s t e e l m e y prevent i t s being

used.

Consideration has

C. ALIGNMENT

The proposed use of quadrupole-focusing magnets has introduced new

I n addition t o the o r ig ina l alignment spec i f i - alignment requirements.

cat ions of s t ra ightness t o 63 m i l s i n any 330-ft length and 125 mils

X.

i n t he over-all length, cur ren t specif icat ione require tha t the! cen ter

of each quadrupole be within 5 m i l s

of t he two adJacent quadrupoles 250 f t away. AB t i g h t 88 t h i s tolerance l a , there is every p o s s i b i l i t y t h a t it can be accomplished through the

use of a proposed opt ical- tool ing system.

of 8 l i n e connecting the cen te r s

- 46 -

XI.

XI. CONTROL SYSTEM STUDIES

A , GENERAL STUDIES During the past quarter the Instrumentation and Control Group has

continued general studies of the operation and maintenance requirements

and of the costs and technical considerations

control-system design.

1. Control Signals

Documentation of all signals and controls

that will influence the

necessary .for ,the opera-

tion of the accelerator is under way. The functions covered to date

include: tion, beam extraction, and maintenance; (b) special transducer problems;

(c) automatic-protection requirements; (d) sector-control functions.

(a) measurement and control signals required for beam opera-

2. Central-Control Area

A conceptual-system-design proposal for central control of the

accelerator was developed. Wctional areas included in this design

are : (a) data communication between central control and accelerator

components, and (b) data handling and display within the central control

area.

configuration that is consistent with the design concept.

A budgetary cost estimate was prepared for a possible equipment

A study was completed defining assumed personnel-communication requirements for the accelerator and its control function, including

construction, maintenance, operation and administration demands. An

over-all system layout and an estimate for an installed cost per unit

was documented for telephone, order wire and service channels, public

address and intercom systems, and the power plants to support these

sys tems . One member of the group has been making design studies for the

Microwave Circuitry Group during the past quarter.

A study of the trigger system is discussed in greater detail below.

B. DESIGN STUDIES

A detailed analysis of the shielding and grounding problems related

to the total Project M system is in progress. presented that resulted in a Ground and Shielding Committee being formed,

with representation f r o m the Systems, Mechanical Engineering, Plant

An initial report was

XI

En@ neering, and Instrumentation and Control groups.

1. Standardization of Connectors

A study is in progress to determine the best types of connectors to meet the project's requirements. Detailed standards and recommendations

will be presented for each connector group when analysis and study are completed.

2. Test-Stand Layout

Layout of the cells for the test stands in the Test Laboratory

Building has been completed.

change over from an under-floor wiring system to an overhead bus-duct

system. Some time was spent in cost studies of the two systems.

The drawings were made on the basis of a

Block diagrams of tentative rf' and focusing systems have been made.

A block wire-route diagram has been made of the rf system.

c. TRIGGEn SYSTEM

1. Outline of System

The trigger system provides synchronization signals for the klystron

modulators, the sub-booster modulators, the gun and associated injection

pulses, monitoring and data-handling equipnent, and other pulsed devices

in the accelerator.

However, it is clear that the trigger system must fulfill certain additional special requirements:

a. The accelerator jitter specification requires that the trigger

system have a jitter not over 5 nanoseconds. b. Compensation for beam-loading effects will be provided through

the trigger system.

c. Control of the rate at which AC-power consumption increases and

drops is to a large degree determined by the trigger system.

d. 24-hour operation requires that certain maintenance f'unctions

and tests must be carried out in the interval between beam pulses.

e. Radiofrequency power must be withheld from the accelerator for

protection of windows in the event of gas bursts or vacuum failure.

f. The gun must be turned off if the beam is misadjusted so as to

reduce hazard to equipment or personnel. g. Multiple-beam operation on Project M must be controll.ed entirely

through the trigger system.

- 4 8 -

XI 0

It should be noted t h a t multiple beams w i l l be used f o r operations,

whether o r not they a re used f o r physics.

routine-maintenance functions depend on using a form of multiple-beam

operation.

Steering,phasing and many

The following system i s proposed as a f i r s t -o rde r conceptual design.

A s ingle high qua l i ty transmission l i n e (10 Mc bandwidth o r b e t t e r ) w i l l

ca r ry i n i t i a t i o n pulses a t 360 pps from a master oscilJ.ator t o l o c a l

s t a t ions e

The pa r t i cu la r r a t e required a t any s t a t ion will be chosen by a

remotely-activated se l ec to r switch.

A gat ing c i r c u i t a t each s t a t i o n w i l l s e l e c t the appropriate pulses

and de l iver them t o a t r igge r booster t h a t w i l l reshape the t r i g g e r

pulse as required. The normal delay adjustments w i l l be introduced

loca l ly . The spec ia l delays f o r beam-loading adjustments a l so w i l l

be introduced loca l ly , by remotely controlled devices.

2. Basic Transmission System

The pulse-time j i t t e r f o r the accelerator system as a whole has been

s e t a t 15 nanoseconds, and f o r the t r i gge r system i t s e l f must be of the

order of 5 nanoseconds. The primary d i s t r ibu t ion l i n e s f o r the t r i g g e r

s igna ls must therefore have a bandwidth of about 200 Mc.

t r i gge r l i n e should be a r ig id , a i r - d i e l e c t r i c l i n e much l i k e the master

r f -dr ive l i n e i n order t o :

equal t o the beam ve loc i ty without cumbersome compensating networks;

(b) eliminate need f o r series-booster amplifiers i n the t r i g g e r l i ne ;

( c ) reduce delay-dis tor t ion of the signals; and (d) provide a s t a b l e

l i n e t h a t i s not e a s i l y damaged. Only one such l i n e need be used.

The main

(a> make the e f f ec t ive t r i gge r ve loc i ty

The main t r igge r l i n e w i l l ca r ry a basic 36O-pps s igna l , a 60-cps

s igna l f o r synchronizing a d iv ider a t each sec tor , and a 1-cps s igna l

fo r single-pulse operation and fo r synchronization of the data-transmission

system.

purpose of kekping the AC-power load more constant.

The choice of a fixed 360-pps basic r a t e w a s made p a r t l y f o r the

If the r epe t i t i on r a t e i n the main l i n e were var iab le only i n s teps

of 60, 120, . .., 360 pps, and a l l the klystrons operated a t one of these r a t e s , the e n t i r e accelerator should thenbe turned off - before t h e repe-

t i t i o n r a t e could be changed. The r a t e of increase of power consumption

XI.

of the high-voltage supplies i s l imi ted t o 3-Mw s teps , 12 Mw/min. r a t e of decrease cannot exceed 18 Mw/min.

ce le ra tor cannot be switched o n a t 60 pps (a 4-Mw s t ep ) , bu t the klystrons

must be turned on i n successive groups.

requires turning of f groups of klystrons i n sequence, changing the r a t e

t o 360, and then turning them on by groups again.

take a minimum of 3 min,

min, t o switch from 60 t o 120 pps and 10 min. t o switch from 120 t o 360 pps.

The AC-power consumption for the high-voltage suppl ies must be reduced

t o zero before changing the r a t e , and then increased t o the desired l eve l .

The I n Stage I, the e n t i r e ac-

To change from 240 t o 360 pps

The operat ion would

In Stage 11, it; would take R minimum of 3-l/2

Using a bas ic 360-pps t r i gge r s igna l and div iders at each sector ,

the r a t e can be switched sector-by-sector d i r e c t l y t o the des i red new

value.

above, but the beam w i l l su f f e r no in te r rupt ion a t a l l .

sumption w i l l change from one l e v e l t o the o ther without the intermediate

period of no load.

The operation w i l l take about ha l f the time given i n the examples

The power con-

It w i l l be recognized t h a t a form of "multiple beam" operation e x i s t s

during the change:

lower ra te ; a port ion of the acce lera tor w i l l operate a t a higher rate

with a "zero-current'' beam on the odd pulses.

the normal beam w i l l continue t o be del ivered a t the

3 . Trigger Selector

The spec i f ica t ion t h a t the acce lera tor operate a t var ious pulse

r a t e s thus implies t h a t each sec tor and sub-hooster be capable of opera-

t i n g a t a d i f f e r e n t r epe t i t i on r a t e ,

r a t e s s t i l l be appropriately synchronized, they must a l l be derived

from a single pulse- t ra in frm the master generator and a s ing le main

t r igge r l i n e .

t h a t passes pulses appropriate t o the desired r a t e and blocks the rest.

A sketch of t he venting of the t r i g g e r pulses is given i n Fig. 11.

Appropriate s e l ec to r s w i l l subdivide the master t r i g g e r s i g n a l t o pro-

duce the desired r a t e f o r each component. The se l ec to r i s shown i n

smewhat more d e t a i l i n Fig. 12,

Since it is necessary t h a t all

The desired operating r a t e w i l l be obtained by a gate

The timing of the output pulses of any channel i s determined so le ly

by the basic 360-pps s igna ls and the individual channel-delay l i n e .

The purpose of the gate is t o transmit se lec ted pulses w i t h m i n i m a l

XI.

- pul s e

se lec tor

master t r igge r

generat or

delay un i t amplifier i G u ~

-

I

. 1

-. amplif ier pulse delay se lec tor ' un i t

* .

Main t r igge r

line (360 PPS

. Sub-Booster (Sector 2)

I

Sub-Booster (Sector 1)

I i I I klystron amplif ier

se lec tor delay amplifier

pulse ' se lec tor ' _.

Modulator i g n i t o r s (Sector 1)

Modulator grids (Sector 1)

Auxiliary equipment (Sector 1)

r 1 I I klystron amplif ier Modulator i gn i to r s

se lec tor (Sector 2)

amplif ier Modulator g r ids delay

(Sector 2) 3 t C .

FIG. 11- -Trigger pulse d is t r ibu t ion .

- 51 -

Main t r i gge r transmission l i n e

r- amplifier

FIG. 12--Detail of sel.ect,or u n i t .

- 52 -

XI.

delay and t o block unwanted pulses (or t o block a l l pulses when required

for l o c a l protect ion of equipment).

automatica.lly closes the gate. The gate i s opened by s igna ls t rans-

mitted from the l o c a l d iv ider , "he aux i l i a ry s igna ls a r e synchronized

so t h a t the in t e rva l between ac t iva t ion of the gate and the pulse t o be

transmitted i s constant, regardless of repetitLon r a t e The: delay

through the gate should therefore be unaffected by the r epe t i t i on rate.

The act ion of t ransmit t ing a pulse

Since a 360-pps r a t e w i l l be used for t he master s igna l , uniform

pulse r a t e s of 60, 120, 180, and 360 will be possible ,

300 o r 240 pps could be obtained by skipping one or two o u t of every

s i x pulses, For the sake of f l e x i b i l i t y and f o r ease of maintenance,

it i s proposed t h a t a t each sec to r a separate t r i gge r rate se l ec to r and

delay u n i t be provided f o r the klystron modulators, f o r the dr ive sub-

booster and fo r any aux i l i a ry equipment, In order t o prevent dropping

the PG and E load i n case of f a i l u r e of the master trigger generator

of the t r i gge r l i n e , the se l ec to r switch w i l l a l s o determine the r a t e

of a stand-by genera.tor a t each sector t h a t w i l l continue t o pulse the

klystron modulators a t the same r a t e , should the master t r i gge r f a i l

t o a r r ive .

A pulse r a t e of

The sectors would no longer be synchronized under such stand-by

operation, and the beam would disappear, b u t the AC power could be re-

duced i n an order ly manner.

The mast,er t r i gge r w i l l cons is t of two pulses of opposite po la r i ty ,

one of which w i l l be used t o f i r e the modulator ignitors, and the second

t o t r i gge r a l l other equipmenf. The delay adjustments need operate only

on the second t r igge r s igna l . I n general , most channel-delays can be

p rese t by l o c a l screwdriver adjustments. The var iab le delay required

t o compensate f o r beam loading must be control led by the beam operator,

bu t can be introduced a t the t r i g g e r booster by remote control .

each rnodulator,special c i r c u i t r y i s provided t o delay the klystron

pulse 5 psec later than normal ( s t i l l within the r f -dr ive pulse) for stand-by warmup and for t e s t ing , o r t o delay the pulse 10 psec (outside

the r f -dr ive pulse) i n case of gas b u r s t o r vacuum failure, l ays w i l l be act ivated by l o c a l o r automatic manual control..

A t

These de-

X I I .

X I I . RESEARCH AREA DESIGN

A. WORK COMPLEmD

1. Gas Scatteringx2

We calculated the beam loss i n the accelerator a r i s i n g from single

sca t te r ing from an exponentially-screened Coulomb f i e l d . We considered

two cases of r a d i a l focusing: none a t a l l , and a very crude version of

r a d i a l focusing. Each case yielded approximately the same answer, namely,

a loss i n be'am current of 0.05$ at a pressure of lo-' mm Hg. The radia-

tion-source strength a r i s ing from t h i s beam loss i s about 100 times less

than we usually assume i n our shielding calculations.

t he t o t a l beam power absorbed i n the machine as 3% of the f i n a l beam

power E I ) . We gave some arguments t h a t indicate t h a t multiple scat-

t e r ing i s unimportant i n the machine because the t o t a l amount of scat-

t e r ing mater ia l i s so s m a l l .

(Usually w e take

f f

2. Activation of t h e Cooling Water

A t the suggestion of W . L. Gallagher w e estimated the formation of

chemical a c t i v i t y and rad ioac t iv i ty i n the cooling water as it passes

through the water jacket next t o the machine.

act ive chemical molecules i s about 1 par t per mil l ion per day (assum-

ing 1 act ive molecule per ion p a i r ) .

l e v e l i s low enough so t h a t we do not plan any fu r the r work.

radioactive nuclide we considered was 0''.

30,000 gallons of water w a s 70 curies .

serious hazard because of the short ha l f - l i f e ( 2 . 1 min).

tha t the infrequent formation of a nuclide w i t h a long l ifetime, e.g. ,

0l6 (7 , 3p2n) Cll or a (y,n) react ion on an impurity, might give rise

t o a more important hazard.

The r a t e of formation of

The calculat ion is rough, but t h i s

The only

The sa tura t ion a c t i v i t y i n

T h i s does not seem t o be a

It is possible

B. CURRENT INVESTIGATIONS

1. Radial-Shower Development

Equipment i s being constructed by J. Cobb t o measure radial-shower

development a t 1 Bev.

under t h e d i rec t ion of R. Hofstadter. It i s s i m i l a r t o a measurement

This work i s being done on the Mark I11 acce lera tor

12H. C. DeStaebler, Jr., "Scattering of Beam Electrons by Residual Gas i n t h e Accelerator," M Report No. 281, Project M, Stanford University, Stanford, California, October 1961 e

- 54 -

XII.

made at 187 MeV by Kantz and I-Iofstadter.13

check of a radial-shower development calculat ion now being done by

C. Zerby a t Oak Ridge.

This w i l l allow a bet ter

2. Induced Activity

We are completing a ca lcu la t ion of the radiat ion l e v e l i n the ac-

ce l e ra to r tunnel when the beam i s o f f t h a t arises from the decay of nuclides made when the e lec t ron beam h i t s t he accelerator .

An important experimental check of t h i s ca lcu la t ion w i l l be made

through t h e kind cooperation of G. Friedlander of Brookhaven National

Laboratory. During the course of the experiment on radial-shower develop-

ment (see B.l. above) we w i l l i r r a d i a t e some copper f o i l s a t d i f f e r e n t

depths i n the shower, and D r . Friedlander w i l l analyze these radiochemically

for us.

3. Shielding Calculations at Oak Ridge

Shortly (within one month) we expect t o receive the r e s u l t s of t he

one-dimensional nuclear-cascade ca lcu la t ion from Oak Ridge. The calcula-

t i o n gives the energy spectrum of nucleons and pions as a funct ion of

depth i n a th i ck shield.

t ranspor t equations for neutrons, protons and charged pions. These four

coupled in tegro-d i f fe ren t ia l equations a re solved numerically on a com-

puter . Then the at tenuat ion ca lcu la t ion w i l l be combined w i t h a source

of p a r t i c l e s based on Ikdr ick ' s ca lcu la t ions of the y i e l d of photo-pions

and photo-nucleons from th i ck t a rge t bremsstrahlung, and t h e r ad ia t ion

l e v e l outs ide of the ear th sh ie ld around the acce lera tor w i l l be ca l -

culated.

The problem i s formulated i n terms of t h e

Another ca lcu la t ion a t Oak Ridge, which i s j u s t ge t t ing started,

concerns the l a t e r a l development of the electron-photon cascade shower,

and espec ia l ly the influence of spec ia l geometrical boundaries on t h e

shower development.

t h e design and evaluation of coll imators, posi t ron rad ia tors and energy-

def ining s l i ts .

The r e s u l t s of t h i s ca lcu la t ion w i l l be use fu l i n

13A. D. Kantz, "Electron-Induced Showers," HEPL Report No. 17, W. W. Hansen Laboratories of Physics, Stanford University, Stanford, Cal i fornia , May 1954.

- 53 -

XII.

4. A t CEXN,nuclear emulsions were exposed under d i f f e ren t depths of

High-Energy Absorption Mean Free Path

baryte concrete (maximum depth 1750 gemm2) t o a beam of 21-Bev protons.

Some of the emulsions are being scanned fo r us by the emulsion group

under Gilbert and Oliver at t h e Lawrence Radiation Laboratory (Livermore),

and t h e scanning i s almost completed. This experiment gives a d i r ec t

measurement of the f luxes of p a r t i c l e s a t large depths i n th i ck shields .

3 . Transverse Shielding

a . We are co l lec t ihg information on a l l aspects of t he shielding

along the accelerator so t h a t we can evaluate the requirements more accurately. So far we have not encountered any information t h a t changes

appreciably our conclusions i n ~ - 2 6 2 . ~ ~ sh ie ld of d i r t 33-ft t h i ck gave a radiat ion l e v e l a t the surface of t h e

sh ie ld t h a t i s about 10'' times radiation-worker tolerance and a l e v e l at

a distance 500 f t from t h e machine t h a t i s about .02 times t h e general-

population tolerance.

amounts. For the general-population l e v e l w e estimated t h a t the uncertainty

f ac to r was about 50.

There we found t h a t a uniform

Both of these leve ls are uncertain by la rge

In our next report we w i l l use t h e r e s u l t s of the Oak Ridge Monte-

Carlo calculat ions on the diffusion and absorption of 1-19 MeV neutrons

i n the atmosphere.

give an idea of the e f f e c t of the ground on the f l u x l e v e l s at the

ground-air in te r face far from the source.

These calculations, which were completed recently,

b . Some addi t ional calculat ions have been made on the neutron f lux t o be expected on the face of the transverse shield. The neutron-source

f lux considered i s taken t o be given by combining the soft-shower photon

spectrum w i t h t he deuteron model f o r the nuclear photo-effect as described

previously. l5

of several thicknesses t h a t are constructed e i t h e r of earth or ordinary

concrete.

ly , and the r e s u l t s give the spectrum of neutrons expected a t any point

on the face of the shield. These spectra show a peak i n t h e neighbor-

hood of 300 MeV and have been integrated t o obtain the t o t a l f lux

The resu l t ing photoneutrons are then at tenuated i n sh ie lds

Oblique and normal attenuation f ac to r s are considered separate-

14H. C. DeStaebler, Jr., M Report No. 262, "A Review of the Trans- verse Shielding Requirements f o r the Stanford Two-Mile Accelerator, " Project M, Stanford University, Stanford, California, April 1961.

M Report No. 227, Project M, Stanford University, Stanford, California, October 1960.

"K. G. Dedrick, "Deuteron Model Calculation of Photonuclear Yields,"

- 36 -

expected at any point on the shield.

l i t t l e from t h a t reported i n ~ - 2 6 2 , ~ ~ except t h a t a more de ta i led explora- t i o n of t he problem has been worked out.

i n an M report i n t he near future .

In general, t h i s work d i f f e r s

The r e su l t s w i l l be published

6. Skyshine

A report i s t o be published soon giving a formulation of the s ingle-

s ca t t e r ing model f o r skyshine problems. I n the method used, shielding

h i l l s cag be e a s i l y considered. This work i s expected t o be useful i n laying out designs f o r the end s t a t i o n i n a rough manner. Eventually,

t he much more accurate (and more expensive) Monte-Carlo techniques must

be applied, but it i s helpful t o ru l e out ce r t a in p o s s i b i l i t i e s i n i t i a l l y ,

l614-262, op. c i t .

- 57 -

X I I I .

X I I I . SITE, BUILDINGS AND UTILITIES

By the end o f the calendar year t h e e f f o r t on Si te , Buildings and

U t i l i t i e s design had reached a r a t e of 60 men/day.

t i o n e f f o r t was rescheduled t o coincide with the ava i l ab i l i t y of con-

s t ruc t ion funds, now estimated a t February 15, 1962.

The first construc-

A document e n t i t l e d "Project M--General Development Plan f o r Con-

This plan i s t o be ventional Fac i l i t i e s " was d is t r ibu ted i n November.

used as a general guide i n scope, schedule and budget f o r a l l t h e f a c i l i t i e s

t h a t are t o be constructed and t h a t are not par t of the accelerator , i t s auxi l ia r ies , or par t of the research equipment. As design progresses

the plan w i l l be revised t o r e f l e c t the l a t e s t planning.

A. MAJOR CONVENTIONAL FACILITIES

The following i s a statement of t h e s t a t u s of the major conventional

f a c i l i t i e s now under design.

1. S i t e Improvements

The locat ion of the entrance road has been selected along Sand H i l l

Road. T i t l e I design has been prepared fo r t h e f i rs t increment of s i te

improvements. This increment i s the first construction work t o be done

on the s i te and i s preparatory t o the f i rs t bui lding construction.

2. S i t e U t i l i t i e s

T i t l e I design of the f irst increment of s i te u t i l i t i e s has been

submitted.

system t h a t w i l l be j o i n t l y developed by Stanford University and The

City of Menlo Park. The source of water i s the l o c a l Hetch Hetchy

Aqueduct.

Plans have become f i r m t o obtain high-quality water from a

Preliminary negotiations have been held with the A.EX and t h e FG and E

Co. t o supply the project e l e c t r i c power. Location and type of service

of a 60-kv l i n e enter ing the project from Alpine Road appears firm.

This l i n e w i l l have a l imited capacity of approximately 15 Mva. The

major source of power w i l l be a 220-kv l i n e t h a t w i l l en te r the pro jec t

from the west end and be d is t r ibu ted t o the accelerator a t 12 kv from a

substation located approximately a t t h e mid-point of the accelerator .

The high-voltage l i n e w i l l l a t e r be extended t o supply large amounts of power t o the End Sta t ion equipment located a t the east end of t h e project .

Planning f o r t he 220-kv l i n e has j u s t s ta r ted .

XIII.

Other u t i l i t i e s are being handled routinely.

3. Test Laporatory Building

T i t l e I1 construction drawings were finished. Construction b ids

w i l l be opened i n the middle of February.

bui lding w i l l be f inished by t h e end of 1962. It i s ant ic ipated t h a t t h i s

4. T i t l e I design has been finished.

5 . Schematic drawings of t h i s complex of buildings have been' approved

Administrat ion and Engineering Building

Shop and General Service Buildings

by the Board of Trustees of Stanford and are now being developed f o r T i t l e I submittal. Both t h i s complex of buildings and the Administra-

t i o n and Engineering Building w i l l be completed ear ly i n the spring of

1963

B. SPECIAL PROBLEMS Investigation of the geology and the s t a b i l i t y of the proposed

bui lding s i te f o r the Accelerator Housing w a s continued.

of a small amount of s o i l movement has been measured near the w e s t end

of the s i t e .

design tolerance of the accelerator alignment, the motion i s ne i ther

well understood nor w e l l documented. Studies are proceeding i n t h i s

area.

An indicat ion

Although the indicated mount of motion is within t h e

Plans were made f o r more temporary space t o house t h e pro jec t during

the construction period.

25,000 sq f t of warehouse-type space t o be temporarily used as office

space.

present Project M Building on campus.

Stanford University w i l l supply an addi t iona l

The new building w i l l be i n the same general locat ion as t he

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X I V .

XIV, WATER SYSTEM

A. PLANT WATER

The plant-water system w i l l be served by the expansion of the City

of Menlo Park's system. This system w i l l serve, besides Project M, a l l Stanford lands i n San Mateo County and all of the lands of t h e Sharon

Estate development.

t o i t s share of the expanded system. 2,000,000 gallons of water storage

w i l l be provided on Sand H i l l a t Elev. approx 483 f t , 1,000,000 gal lons

being reserved f o r F'roQect M use. Elev. 4-85 f t i s high enough t o pro- vide adequate gravi ty f i r e - f igh t ing flow pressure. Plans and negotia-

t i ons are proceeding toward the i n s t a l l a t i o n of enough of t he p lan t -

water system t o serve the laboratory area at t h e t i m e the Test Labora-

to ry Building i s complete.

Project M w i l l pay a connection charge equivalent

B. COOLING WATER

There w i l l be three cooling-tower s t a t ions serving the p l an t : i one large one located about halmay along the two-mile acce lera tor t o

serve the Klystron Gallery and Accelerator Housing, a second l a rge one

located near the end s t a t ions t o serve them and the beam switchyard,

and a t h i r d and smaller s t a t i o n t o serve the buildings i n the laboratory

area. The las t named w i l l be constructed first, t o coincide with the

construction of the Test Laboratory Building.

The following arrangement w a s recommended i n ABA Report, "Heat

Transfer System Study" (ABA-3), f o r cooling the two-mile accelerator .

Cooling-tower water would be d is t r ibu ted t o f i f t e e n iden t i ca l heat-

exchanger i n s t a l l a t i o n s spaced about 640 f t apar t along the length of the accelerator . A t these points the low-conductivity, c losed-circui t

cooling-water systems serving klystrons, modulators, e tc . , w i l l give up

heat t o the cooling-tower water system. The heat would, i n turn, be

given up t o the atmosphere a t t h e cen t r a l cooling tower. T h i s recom-

mendation w i l l be reviewed r e l a t ive t o the poss ib i l i t y of having only

one b i g cen t r a l heat-exchanger i n s t a l l a t i o n ra ther than t h e f i f t e e n

described above.

In the case of the beam switchyard and end-station area, cooling-

tower water w i l l be d is t r ibu ted t o heat-exchanger i n s t a l l a t i o n s located

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XIV .

adjacent t o the major cooling-load centers where the exchangers w i l l

pick up the heat from the closed-circuit , low-conductivity cooling water. The laboratory area cooling-water system i s i n t he de ta i led design

stage b

The deionizers w i l l produce water of 5OO,OOO ohms minimum spec i f ic

res is tance with an oxygen content of 0 .1 ppm maximum.

C. BLOW-DOWN WATER

A study w i l l be made of the possible uses of t h e blow-down water from the cooling towers.

and used f o r ProJect M lands i r r i g a t i o n and/or t o augment the water

supply t o Lake Lagunita.

There i s a poss ib i l i t y tha t it could be s tored

D. rnSEARCK AND D E V E L O r n

See Section 111, Accelerator Structure Studies, f o r research and

development work on cooling the accelerator s t ructure .

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XV. HEATING AND VENTILATING

Detailed d.esign of the heating and vent i la t ing system for the Test Laboratory Building i s complete.

T i t l e I design f o r heating, vent i la t ing and air conditioning the

Engineering and Administration Buildings hss been completed.

T i t l e I design f o r U t i l i t y Building A has been completed and de-

ta i led ,des ign s ta r ted .

air-compressor equipment, air-conditioning re f r igera t ion equipment, and

the emergency-power d i e s e l generator. The cen t r a l plant w i l l serve a l l

of t he buildings i n the laboratory area.

This bui lding w i l l house a central-heating plant ,

Yard piping i s being prepared i n a separate T i t l e I package.

ABA has completed a report en t i t l ed , "Humidity i n t h e Accelerator

Housing" (ABA-25) out l ining a couple of a l t e rna t ives i n ven t i l a t ing

the Accelerator Housing.

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