Salzau 21.01.2003 M. Körfer, DESY 1 Layout and Functionality of Collimator System Purpose of the Collimator System Layout Sub-Systems Transversal/ Energy.

M. Körfer, DESY1Salzau 21.01.2003

Layout and Functionality of Collimator System

Purpose of the Collimator System

Layout

Sub-SystemsTransversal/ Energy CollimationFast Orbit Correction System Matching Sections

Diagnostic Concept



Purpose: Protection of Permanent Magnet Undulator

transversal collimation beam halo separationenergy collimation dark current separation

TTF2 Design for high average beam power• 72 kW average beam power

1 nC, 800 s, 9 MHz, 10 Hz, 1 GeV

Collimator Scheme

Energy & Transversal Collimation

Beam

Design take into account:beam dynamicsmaterial scienceinteraction of e- and collimator


Experience of the TTF1 collimator

1) energy collimation needed absorption of dark current

2) offset of collimator and undulator axis secondary particle(mostly low energy photons !) escaping the absorber systemshould not hit the undulator

Additional Functionality : saves tunnel length by including

a) fast orbit correction system and b) optics matching



Layout of Collimator System

Start: 143.35 mEnd: 166.11 mTotal length: 22.76 mTCOL: 9.02 mECOL: 6.95 mMATCH: 6.79 mDipole: 3.5 ˚ horizontalOffset: 400 mm

Bypass

TCOL

ECOL

MATCH

Beam


Diagnostic Concept

Beam

Quad+BPMDark Current Dipole KickerCollimatorToroid OTR-Wire

Steerer

MATCH ECOL TCOL


Transverse Collimation

Beam

TCOL

TCOL

TQA

TQA

Kicker

Steerer

Steerer

TQA

KickerBypass Dipole

ToroidDCM

Copper versus Titanium:• better temperature conductivity • better electrical conductivity• better Collimator efficiency• less stress limit T=180º

Copper Collimatortotal length: 500 mmmover support: hor./vert.position accuracy: 15 m

TCOL


Energy Collimator

Beam

ECOL

ECOL

TQB+BPM

TQB

TQB+BPM

TSB

TSB

Steerer

Steerer

Steerer

TDHECOL

TDH

ECOL dispersive Section at the end D = 0, D` = 0 Quadrupoles inbetween Dipoles compensation of higher order dispersion by sextupoles orbit at the undulator entrance

independent of energy within 5%

-0.06 -0.04 -0.02 0.00 0.02 0.04 0.06-2.00

-1.75

-1.50

-1.25

-1.00

-0.75

-0.50

-0.25

0.00

0.25

DOGLEG, Orbit versus Energy Offset

Orb

it,

en

d o

f b

ea

mli

ne

[m

m]

E / E [%]

due to quadrupoles

ECOL 400 mm beam path offset avoids direct photon shower into the undulator


CSR-Effect and Slice-Emittance Growth

Collimator Dogleg

Input:l=50mn=2 mm mradE=1.0 GeV

Output:l=50mslice=2.2 mm mradproj.=2.8 mm mradE/Ecorr= 0.05 %

Trafic 4B

eam

ECOL

ECOL

TQB+BPM

TQB

TQB+BPM

TSB

TSB

Steerer

Steerer

Steerer

TDHECOL

TDH


%30

E

E capture particle

max. aperture at minimum

%30

E

E energy bandwidth for R=2 mm(without interaction with pipe)

Collimator Efficiency: calculated with• gaussean beam profile• back scattering• secondary particle

6101

ParticleStartBeame

ParticleLossUndulator

E

E

Collimation and Efficiency

Undulator Chamber

Dark Current Module

blue curve

Collimator Aperture


Collimator

a1a2

a3

z

100 mm

z[mm] a1[mm] a2[mm] a3[mm] rms[kV/nC] @ 50m

0 2 -- 17 153

200 2 4.5 17 113

reduction of uncorr. energy-spread by 50%

Impact of wakefields at TTF2

Vacuum Pipe Conductivity

Material r[mm] rms @50m [kV/nC/m]

stainless steel 17 12.2copper 17 3.1TESLA Cavity 39 9.6

Consequence:

1. copper coated vacuum pipes2. avoiding steps inside the pipes3. Bellow RF-shielding

Longitudinal Wakefields und Energy Spread


Matching Section MATCH

Fast orbit correction system:

H-Kicker > 3 h

V-Kicker > 2 v

at undulator entrance

Optic Matching with downstream section

Beam

Kicker

Kicker

TQB+BPM

TQB+BPM

Steerer

Steerer

SteererPhasemonitor, Toroid, OTR

TQB

TQB

Salzau 21.01.2003 M. Körfer, DESY 1 Layout and Functionality of Collimator System Purpose of the Collimator System Layout Sub-Systems Transversal/ Energy.

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