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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 . Beam. Layout and Functionality of Collimator System.
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Layout and Functionality of Collimator System Purpose of the Collimator System Layout Sub-Systems Transversal/ Energy Collimation Fast Orbit Correction System Matching SectionsDiagnostic Concept M. Körfer, DESY
Beam 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 Design take into account: beam dynamics material science interaction of e- and collimator Energy & Transversal Collimation M. Körfer, DESY
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 M. Körfer, DESY
Layout of Collimator System MATCH Bypass ECOL Beam 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 TCOL M. Körfer, DESY
Diagnostic Concept Steerer Beam Toroid Dark Current OTR-Wire Dipole Collimator Kicker Quad+BPM ECOL TCOL MATCH M. Körfer, DESY
Transverse Collimation TQA Copper Collimator total length: 500 mm mover support: hor./vert. position accuracy: 15 m Steerer TCOL TQA TCOL Kicker Bypass Dipole Kicker Steerer Beam TCOL • Copper versus Titanium: • better temperature conductivity • better electrical conductivity • better Collimator efficiency • less stress limit T=180º TQA Toroid DCM M. Körfer, DESY
TDH ECOL Steerer TSB TQB+BPM Steerer TQB Beam ECOL TQB+BPM TSB Steerer ECOL due to quadrupoles TDH Energy Collimator ECOL dispersive Section at the endD = 0, D` = 0 Quadrupoles inbetween Dipoles compensation of higher order dispersion by sextupoles orbit at the undulator entrance independent of energy within 5% ECOL 400 mmbeam path offset avoids direct photon shower into the undulator M. Körfer, DESY
TDH ECOL Steerer TSB TQB+BPM Steerer TQB Beam ECOL TQB+BPM TSB Steerer ECOL TDH CSR-Effect and Slice-Emittance Growth Collimator Dogleg Trafic 4 Input: l=50m n=2 mm mrad E=1.0 GeV Output: l=50m slice=2.2 mm mrad proj.=2.8 mm mrad E/Ecorr= 0.05 % M. Körfer, DESY
Undulator Chamber Dark Current Module Collimation and Efficiency Collimator Aperture • Collimator Efficiency: • calculated with • gaussean beam profile • back scattering • secondary particle blue curve max. aperture at minimum energy bandwidth for R=2 mm (without interaction with pipe) capture particle M. Körfer, DESY
Collimator Impact of wakefields at TTF2 100 mm a1 a2 Vacuum Pipe Conductivity a3 Material r[mm] rms @50m [kV/nC/m] stainless steel 17 12.2 copper 17 3.1 TESLA Cavity 39 9.6 z z[mm] a1[mm] a2[mm] a3[mm] rms[kV/nC] @ 50m 0 2 -- 17 153 200 2 4.5 17 113 • Consequence: • copper coated vacuum pipes • avoiding steps inside the pipes • Bellow RF-shielding reduction of uncorr. energy-spread by 50% Longitudinal Wakefields und Energy Spread M. Körfer, DESY
Matching Section MATCH Optic Matching with downstream section Phasemonitor, Toroid, OTR Steerer Fast orbit correction system: H-Kicker > 3h V-Kicker > 2v at undulator entrance TQB+BPM Kicker TQB Beam Kicker Steerer TQB+BPM TQB Steerer M. Körfer, DESY