Salzau 21.01.2003 M. Körfer, DESY 1 Layout and Functionality of Collimator System Purpose of the...
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Transcript of Salzau 21.01.2003 M. Körfer, DESY 1 Layout and Functionality of Collimator System Purpose of the...
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
M. Körfer, DESY2Salzau 21.01.2003
Layout and Functionality of Collimator System
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
M. Körfer, DESY3Salzau 21.01.2003
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 and Functionality of Collimator System
M. Körfer, DESY4Salzau 21.01.2003
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
M. Körfer, DESY5Salzau 21.01.2003
Diagnostic Concept
Beam
Quad+BPMDark Current Dipole KickerCollimatorToroid OTR-Wire
Steerer
MATCH ECOL TCOL
M. Körfer, DESY6Salzau 21.01.2003
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
M. Körfer, DESY7Salzau 21.01.2003
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
M. Körfer, DESY8Salzau 21.01.2003
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
M. Körfer, DESY9Salzau 21.01.2003
%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
M. Körfer, DESY10Salzau 21.01.2003
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
M. Körfer, DESY11Salzau 21.01.2003
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