SUPERC O NDUC T ING 112 M HZ Q W R ELEC T RON G U N*f time and liq ellen t. hode rod was uple r (FPC) e cryomodul n in Figure 2 surrounded b, another laye metal). ycles: weldin nner

A

h

Npt

R

w

p

h

Fp

t

b

S. Belome

Abstract Brookhaven

have designed quarter-wave cold test of thNiowave. Thepresents the cothe cryomodudifferent photocooling proof-options, one foone for a diam

A quarter-wRF (SRF) eleccooling hadronsufficiently cowavelengths). long electron effects and enshould be suitacurrent electro

A 112 MHzcold-tested in [3]. This is thsuccessfully. Infabrication, prplans. This guSRF gun to bhadrons in eRH

112

The cavity gFigure 1 showparameters, suappear nearly(recessed cathfocus the beamthe high intenshape has higbut these field

__________________________

* Work is supporContract No. DEBrook UniversityU.S. DOE. Workcontract No. DE-#sbelomestnykh@

SUPERCO

stnykh#,1, I. B. Sieg

1) Brook2) St

n National Laand fabricatedresonator (QWe QWR cryome paper descriold test results,ule. Future expocathodes and -of-principle exfor multi-alkali

mond-amplified

INTRODwave resonatorctron gun was n beams in RHompact even a

The long wabunches, thu

nabling high buable for experi

on beams. z QWR gun w

collaboration he lowest freqn this paper wresent the coldun will also serbe used for cHIC.

MHZ GUNFABRIC

geometry was ws the model usummarized in Ty electrostaticode, as shownm and compennsity electron her electric filevels are cont

__________________

rted by BrookhaveE-AC02-98CH108y is supported undk at Niowave is [email protected]

ONDUCT

Ben-Zvi1,2, Cgel3, J. Skaritkhaven Natiotony Brook

3) Niowa

aboratory and d a superconduWR) electron module has beeibes the cryom, and outline pperiments incluse for the co

xperiment. Twi photocathode photocathode,

DUCTION r concept of sproposed at BN

HIC [1, 2]. QWRat low RF freavelength allous minimizingunch charge. Aiments requirin

was designed, between BNL

quency SRF ge describe the

d test results, arve as a prototycoherent elect

N DESIGN ACATION designed usingsed to calculatTable 1. Sincec, a Pierce-t

n in the figure)nsate for the sbeam. The P

elds away frotrolled in the d

en Science Associa86 with the U.S. D

der grant DE-SC00pported by the U.S1

TING 112 M

C.H. Boulwtka1, R. Thanonal LaboratUniversity, Save, Inc., La

Niowave, Incucting 112 MH

gun. The firsen completed amodule design

plans to upgradlude studies ooherent electro

wo cathode stales and the othe, are discussed

superconductinNL for electroRs can be madequencies (lonows to producg space chargAlso, such gunng high averag

fabricated, anL and Niowavgun ever testegun design anand outline ouype for a futurron cooling o

AND

g Superfish [4]te the cavity RFe the fields witype geometr can be used t

space charge oPierce electrodm the cathode

design.

ates, LLC under DOE. Work at Ston005713 with the S. DOE under SBI

MHZ QW

are3, X. Chan1, M. Winotory, Upton, Stony Brook

ansing, MI 48

c. Hz

st at n, de of on lk er d.

ng n

de ng ce ge ns ge

nd ve ed nd ur re of

]. F ll

ry to of de e,

Table 1:

Paramet

Frequenc

R/Q (lina

Geometry

Quality f

Operating

Epk/Vacc

Epk/Ecath

Bpk/Vacc

Length

Aperture

Maximum

Figure 1:

Fig

ny

IR

WR ELECT

ang1, T.L. Grwski3, Q. WNY 11973-5

k, NY 117948906, U.S.A

RF parameter

ter

cy

ac definition)

y factor G

factor Q0 w/o cat

g temperature

m diameter

Cavity geome

gure 2: 112 MH

TRON GU

rimm3, X. LiWu1, T. Xin1,2

5000, U.S.A4, U.S.A. A.

rs of the 112 M

thode insert

etry used in Sup

Hz electron gun

UN*

iang1,2, T. Ra

A.

MHz SRF gun c

Value

112 MH

126 Ohm

38.2 Oh

> 3.51

4.5 K

19.1 m-1

2.63

36.4 mT

1.1 m

0.1 m

0.42 m

perfish calcula

n cryomodule.

ao1,

avity

Hz

m

hm

09

1

T/MV

ations.

Proceedings of SRF2011, Chicago, IL USA MOPO054

05 Cavity design 223

t

t

p

pt

rh

tv

t

t

F

The compleThe niobium cthe superinsulof superinsulat

Electron bethe niobium bconductor halvall niobium we

Figure 3: El

The stainlescavity prior to cooling jacket.pressure rinsecryomodule’s steel. The vessshield. Due tcryomodule wcarry out anassembly. Thecleanroom wipick-up probethe cryomoduchecked and co

The cooldosupply to theovernight witapproximatelyflanges to jusliquid nitrogenflanges were c130 K, with threaching 100 Khelium took pcooled at a ratthe time in thvessel sensor and the liquidsummary, the transition in apof the liquid cavity cooldowto boiling) was

For this testfundamental RFigure 4. An

te cryomodulecavity in a heation, liquid ntion, and magnam welding in

beam tube; weves; welding telding of the ca

lectron beam w

ss steel heliumchemical etch

. The cavity waed in the Cvacuum vesse

sel is demagneto the size of

was easier and n intermediate cavity was ith the cathode and beamlineule was compold shocked w

FIRST COown began we thermal shth exhaust gay 150 K. This t below 200 Kn pre-cool of tcooled at a ratehe temperatureK in about 2 hoplace after thte of 2 K/min fhe “Q diseasereached 4.4 K

d helium vesscavity was co

pproximately nitrogen pre-

wn (in terms os therefore exct, a copper catRF power coexternal (to th

e design is showlium vessel is nitrogen shieldnetic shield (muncluded four celding of the ithe subassembavity shown in

welded 112 MH

m vessel was whing of niobiumas chemically eClass 100 clel is made froetized and actsf this cavity, more efficient

te test beforhermetically

de assembly, pe vacuum complete, it was ith liquid nitro

OLD TEST with opening lhield. It was as from the s

procedure cooK. This was fothe helium vese of 10 K/min de monitors on tours. The switcat. The cavityfrom 130 K toe” range. The

K in approximsel was full inooled to the s3.5 hours from-cool. The effof time and liqcellent. thode rod wasoupler (FPC) he cryomodul

wn in Figure 2surrounded b

d, another layeu metal). cycles: weldininner and outebly; completinn Figure 3.

Hz Nb cavity.

welded onto thm and acted as etched and higleanroom. Thom low carbos as a magneti

testing in tht than trying tre cryomodul

sealed in thpower couple

mponents. Oncvacuum lea

ogen.

liquid nitrogecooled stabl

shield tubes aoled the cavit

followed by thssel. The cavitdown to arounthe vessel itselchover to liquiy flanges wero 10 K, limitine liquid helium

mately one houn 1.5 hours. I

superconductinm the beginninficiency of th

quid helium los

also used as as shown i

e) RF networ

2. y

er

ng er ng

he a

gh he n ic he to le he r,

ce ak

en ly at ty he ty nd lf id re ng m ur In ng ng he st

a in rk

was usedresonant observed The difficthe extremmode wa476.5 MHfundamenposition ocavity. Re

Figur

F

RF powof loadedbe easily Q of as hto the gaimposed 2 mrem/haround thcathode/cregion asconsistentsimulationQ at ~ 0.5cavity qufield emiQ degraconfidenc1.5 to 2.5helium bo

d for fine-tunimodes. The at 113.0 MHz

culty in locatinmely narrow bas also obserHz. The adjusntal mode wof the cathode esults are show

re 4: Testing se

Figure 5: Load

wer scans wered Q. The observ

conditioned awhigh as 109 waap voltage up

by the radhr, as there wahe cryomodule.coupler is inses shown in tht with the ns. Further, ve5 MV due to fi

uenches at highssion sites cou

adation at thce that this gun5 MV. The staoil-off, is less t

ing the couplfundamental

z within 2 houng the mode frandwidth of thrved at high stability of th

was measured and observing

wn in Figure 5.

etup for first cr

ded Q vs. catho

e performed atved multipactinway. As showns observed at to about 0.5

diation safetyas no dedicated. The cavity Q erted further

he lower curvone expecte

ery little degraield emission wh field were seuld potentially hese field len can perform atic heat leak, than 7 W

ling and searccavity mode

urs of the coolrequency was he mode. The “

Q and locathe coupling t

by changing the loaded Q

ryogenic RF tes

de position.

t two extreme vng barriers pron in Figure 6, fields correspoMV. The limi

y requiremend radiation shiis reduced whinto the high

ve. The reducted from comadation of the was observed aeen. Condition

eliminate all evels, giving

in the desired estimated fro

ch for e was ldown. due to “5λ/4” ted at to the g the of the

st.

values oved to

cavity onding it was

nts of ielding hen the h field tion is mputer cavity

and no ning of

cavity good range

om the

MOPO054 Proceedings of SRF2011, Chicago, IL USA

224 05 Cavity design

F

P

un

F

vt

Figure 6: Cavcoupler in two

GThe near fu

gun will condiamond-amplit will be usedfor the coherenPoP) experimaforementionefollowing mod The low-c

with a stCode requ

The vacuuallow easy

A second Cryogenic

the BNL r Stainless

cryostat w Cathode s

designed diamond-

As the frequencypipe type

The FPC anused in the Nnew RF powerstalk assemblieFigure 7. The 100 kHz. Thexternal qualitdifferent CeCvoltage from 1to 3 nC at the b

vity Q vs. gao different posit

GUN MODuture experimencentrate on lified photocatd to produce hnt electron coo

ment at BNLed experimentsdifications: carbon-steel vatainless steel ouirements. um vessel willy access to insmagnetic shielc stack will brefrigeration systeel bellows

will be copper pstalks, inserts a

and fabricaamplified photCeC PoP e

y tuning, the nwill be also us

nd the cathode NPS prototype

r coupler / freqes for photocatfrequency tun

he FPC will ty factor from

C PoP operatin1 MV to 2 MVbunch repletion

ap voltage wittions.

IFICATIONents with the studies of m

thodes. Furtherhigh-charge eloling proof-of-

L [5]. To bes, the gun wi

acuum vessel wone to meet A

l have flanges ide of the cryold will be adde

be modified toystem. and beam tuplated to reducand a load lockated for mutocathodes. experiment rnew FPC of ased for tuning. stalks will be 500 MHz SRF

quency tuner athodes are bein

ner will have raprovide adjus

m 3107 to 1.2ng conditions

V and bunch chn frequency of

th the cathode

N 112 MHz SRF

multi-alkali anr down the linlectron bunchef-principle (CeCe used in thill undergo th

will be replaceASME Pressur

on both ends tostat. ed. o interface wit

ubes inside thce RF losses. k system will bulti-alkali an

equires cavita coaxial beam

similar to thosF gun [6]. Thand the cathodng designed [7]ange of at leasstability of th2108 to cove

with the gaharge from 1 nCf 78 kHz.

e/

F nd ne es C

he he

ed re

to

th

he

be nd

ty m

se he de ], st

he er ap C

Figure 7:and FPC.

We ha112 MHzThe gunperformanThe obseThere wavoltage osafety req

We plphotocathelectron c

[1] A. Fefor LAcce

[2] A. FeRHICChin

[3] S. Beof BElectPAC

[4] K. HCompCylin(1976

[5] G. WFEL-of PA

[6] S. P. 500 MFEL2

[7] T. XiCoupSupeMOP

SRF gun cryo

SUave successfulz SRF gun ban cryomodulence. RF losserved multipactas no cavity of ~ 0.5 MV wquirements. an to use th

hodes and procooling proof-o

REFedotov, et al., Low-Energy Relerator AP Noedotov, et al., “C Program,” Pa, MOM2MCIelomestnykh, eBNL Supercotron Gun A’2011, TUP051albach and Rputer Programndrical Symm6) 213-222.

Wang, et al., “P-based Coheren

AC’2011, THOBNiles, et al.,

MHz Quater-W2010, WEPB28in, et al., “Depler and Photoerconducting EPO014.

module with th

UMMARY lly designed aased on a quare demonstrates are consistenting barriers wquenches and

was limited on

his SRF gun ovide electronof-principle exp

FERENCES“Feasibility o

RHIC Operatioote C-A/AP/30“Electron Cool

Proceedings of IO01, p. 11 (20et al., “Design onducting 112Applications,”1 (2011).

R.F. Holsinger, m for Evaluationmetry,” Partic

Proof-of-Princnt Electron CoBN3 (2011). “NPS Prototy

Wave Gun Upd8 (2010). esign of the Focathode InserElectron Gun

he new cathode

and cold-testerter-wave reso

ed good cryont with simula

were easy to prd the achievenly by the rad

to study difns for the coperiment at BN

S of Electron Con,” BNL Co7(April 2008).ling for Low-E

f COOL09, Lan009).

and First Col2 MHz QWR Proceeding

“SUPERFISHn of Rf Cavitiecle Accelerato

iple Experimeooling,” Procee

ype Superconddate,” Proceedi

Fundamental Prts for the 112,” this confe

e stalk

ed the onator. ogenic ations. rocess. d gap diation

fferent oherent NL.

ooling ollider-

Energy nzhou,

ld Test R for

gs of

H – A es with ors 7

ent for edings

ducting ings of

Power 2 MHz erence,

Proceedings of SRF2011, Chicago, IL USA MOPO054

05 Cavity design 225