Transcript No Slide Title

Layout and Functionality of Collimator System
Purpose of the Collimator System
Layout
Sub-Systems
Transversal/ Energy Collimation
Fast Orbit Correction System
Matching Sections
Diagnostic Concept
Salzau 21.01.2003
M. Körfer, DESY
1
Layout and Functionality of Collimator System
Purpose: Protection of Permanent Magnet Undulator
transversal collimation  beam halo separation
energy 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
Beam
Design take into account:
beam dynamics
material science
interaction of e- and collimator
Energy & Transversal Collimation
Salzau 21.01.2003
M. Körfer, DESY
2
Layout and Functionality of Collimator System
Additional Functionality : saves tunnel length by including
a) fast orbit correction system and
b) optics matching
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 system
should not hit the undulator
Salzau 21.01.2003
M. Körfer, DESY
3
Layout of Collimator System
MATCH
Bypass
ECOL
Start: 143.35 m
End: 166.11 m
Total length: 22.76 m
TCOL: 9.02 m
ECOL: 6.95 m
MATCH: 6.79 m
Dipole: 3.5 ˚ horizontal
Offset: 400 mm
Salzau 21.01.2003
TCOL
M. Körfer, DESY
4
Diagnostic Concept
Steerer
Toroid
Dark Current
MATCH
Salzau 21.01.2003
OTR-Wire
Dipole Collimator
ECOL
M. Körfer, DESY
Kicker
Quad+BPM
TCOL
5
Transverse Collimation
Copper Collimator
total length:
500 mm
mover support:
hor./vert.
position accuracy: 15 m
TQA
Steerer
TQA
TCOL
Kicker
TCOL
Bypass Dipole
Kicker
Steerer
TCOL
Copper versus Titanium:
• better temperature conductivity
• better electrical conductivity
• better Collimator efficiency
• less stress limit T=180º
Salzau 21.01.2003
TQA
Toroid
DCM
M. Körfer, DESY
6
Energy Collimator
ECOL
TDH
 dispersive Section
 at the end D = 0, D` = 0
Steerer
 Quadrupoles inbetween Dipoles
 compensation of higher order
TSB
dispersion by sextupoles
 orbit at the undulator entrance TQB+BPM
independent of energy within 5%
Steerer
Orbit, end of beamline [mm]
0.25
ECOL
TQB
DOGLEG, Orbit versus Energy Offset
0.00
-0.25
ECOL
-0.50
-0.75
TQB+BPM
TSB
Steerer
-1.00
-1.25
-1.50
-1.75
-2.00
-0.06
due to quadrupoles
-0.04
-0.02
0.00
0.02
0.04
0.06
ECOL
 E / E [%]
ECOL  400 mm beam path offset avoids
direct photon shower into the undulator
Salzau 21.01.2003
M. Körfer, DESY
TDH
7
CSR-Effect and Slice-Emittance Growth
Collimator Dogleg
Trafic 4
Input:
l=50m
n=2 mm mrad
TDH
Steerer
ECOL
TSB
TQB+BPM
Steerer
TQB
E=1.0 GeV
ECOL
Output:
TQB+BPM
TSB
Steerer
l=50m
slice=2.2 mm mrad
proj.=2.8 mm mrad
E/Ecorr= 0.05 %
ECOL
TDH
Salzau 21.01.2003
M. Körfer, DESY
8
Collimation and Efficiency
Collimator Aperture
Collimator Efficiency:
Undulator Chamber
calculated with
• gaussean beam profile
• back scattering
• secondary particle
Undulator
Loss  Particle
Dark Current Module
blue curve
max. aperture at minimum
E
 3%
E0
energy bandwidth for R=2 mm
(without interaction with pipe)
E
 3%
E
Salzau
21.01.2003
0
E
E
 1 106
e  Beam
Start  Particle
capture particle
M. Körfer, DESY
9
Longitudinal Wakefields und Energy Spread
Collimator
Impact of wakefields at TTF2
100 mm
Vacuum Pipe Conductivity
a2 a1
Material
a3
z
z[mm] a1[mm] a2[mm] a3[mm]
rms[kV/nC]
stainless steel
copper
TESLA Cavity
r[mm]
 rms @50m
17
17
39
[kV/nC/m]
12.2
3.1
9.6
@ 50m
0
2
--
17
153
200
2
4.5
17
113
reduction of uncorr. energy-spread by
50%
Salzau 21.01.2003
Consequence:
1.
2.
3.
M. Körfer, DESY
copper coated vacuum pipes
avoiding steps inside the pipes
Bellow RF-shielding
10
Matching Section MATCH
Optic Matching with
downstream section
Fast orbit correction
system:
H-Kicker >  3 h
V-Kicker >  2 v
at undulator entrance
Phasemonitor, Toroid, OTR
Steerer
TQB+BPM
Kicker
TQB
Kicker
Steerer
TQB+BPM
TQB
Steerer
Salzau 21.01.2003
M. Körfer, DESY
11