1. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 Injector Physics C.Limborg-Deprey Diagnostics and Commissioning GTL measurements Thermal emittance measurements Gun spectrometer Straight Ahead spectrometer Energy measurements Slice emittance measurements (both planes) Low Charge tunings RF studies L01 dual feed RF gun dual feed mode 0 studies

2. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 Gun S1S2 L0-1 19.8MV/m L0-2 24 MV/m ‘Laser Heater’ ‘RF Deflecting cavity’ TCAV1 3 screen emittance measurement 6 MeV  = 1.6  m  ,un. = 3keV 63 MeV  = 1.08  m  ,un. = 3keV 135 MeV  = 1.07  m  ,un. = 3keV DL1 135 MeV  = 1.07  m  ,un. = 40keV Spectrometer Linac tunnel UV Laser 200  J,  = 255 nm, 10ps, r = 1.2 mm Spectrometer

3. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 ‘Laser Heater’ ‘RF Deflecting cavity’ TCAV1 3 screen emittance measurement Gun Spectrometer Linac tunnel Straight Ahead Spectrometer Uniformity + Thermal emittance 1243 Commissioning Diagnostics YAG1YAG2

4. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 Above: Laser cathode image of air force mask in laser room. Below: Resulting electron beam at pop 2. Above: Laser cathode image with mask removed showing smooth profile. Below: Resulting electron beam showing hot spot of emission. Laser masking of cathode image at DUVFEL Courtesy W.Graves Point-to-point imaging of cathode on YAG1 Emission uniformity 1

5. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 YAG2 == Image of divergence of source Assumes  th = 0.6 mm.mrad Very good resolution of divergence Infinite-to-point imaging what type of momentum distribution? Thermal Emittance 1

6. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 Gun Spectrometer Energy Absolute energy Alignment using laser Spectrometer field calibration Correlated Energy Spread for all charges Uncorrelated energy spread for low charges Introducing a time-energy correlation (varying injection phase) Slice thermal emittance Relay imaging system from YAG1 to spectrometer screens Point-to-point imaging in both planes Uniformity of line density Energy Absolute energy Alignment using laser Spectrometer field calibration Correlated Energy Spread for all charges Uncorrelated energy spread for low charges Introducing a time-energy correlation (varying injection phase) Slice thermal emittance Relay imaging system from YAG1 to spectrometer screens Point-to-point imaging in both planes Uniformity of line density YAG01 Spectrometer YAGG1 YAGG2 Quadrupoles 2

7. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 High Charge Operation : 1nC Nominal tuning – no quadrupole on – Very good linearity Longitudinal at YAG1 YAGG1

8. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 Resolves line density uniformity at high charge YAG1  RF + 25  / nominal Quadrupoles on for manageable image size Resolves modulation +/- 8% modulation on laser beam

9. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 Laser Heater Transverse RF Cavity OTR Emittance Screens DL1 Bend Straight Ahead Spectrometer 135MeV Diagnostics Point-to-point imaging of the 75  m waist (OTR5) Horizontal slice emittance Vertical deflecting cavity + 3screen Vertical slice emittance Quad scan + spectrometer Quad Scan + Dogleg bend  Verification of thermal emittance Longitudinal Phase space Vertical deflecting cavity + spectrometer Efficiency of laser heater (spectrometer has 10 keV resolution) Horizontal slice emittance Vertical deflecting cavity + 3screen Vertical slice emittance Quad scan + spectrometer Quad Scan + Dogleg bend  Verification of thermal emittance Longitudinal Phase space Vertical deflecting cavity + spectrometer Efficiency of laser heater (spectrometer has 10 keV resolution) 6D beam measurements

10. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 Longitudinal Phase Space at waist Transverse deflecting cavity  y / time correlation (  1mrad over 10ps ) Spectrometer  x / energy correlation From PARMELA simulations (assuming 1  m emittance), resolution of less than 10 keV rmsfwhm Spectrometer + Vertical deflecting cavity  Direct longitudinal Phase Space representation

11. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 Alternate tunings for improving   th = 0.6 mm.mrad per mm laser spot size NameQ (nC) Laser pulse (ps) r (mm)  th (  m.rad)  80 (  m.rad)  RF (  )   80  5% Nominal1101.20.720.9322.5 1 nC, 17.5 ps117.50.850.50.75331.5 0.2nC,10ps0.2100.390.2340.38372.5 0.2nC,5ps0.250.420.250.37325 1nC 0.2nC

12. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 RF Studies- L01 coupler Dipole moment Quadrupole moment From Z.Li, L.Xiao, ACD/SLAC

13. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 RF Gun – Racetrack in full cell 2d-: no port = benchmark omega3p/sf 3d-cylin: with coupling ports- cell cylindrical 3d-rtrack: with coupling ports- cell racetrack Full : with laser ports + racetrack Full retuned: with laser ports + racetrack+ retuned From L.Xiao, ACD/SLAC bb d  x =  y =0.88   x = 0.96  y =1.01  x =  y =  0.90  x = 0.97,  y = 0.99  x = 0.91,  y = 0.915

14. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 RF Gun – Mode 0 studies dF3.4 MHz8 MHz 3  s, V cath. in 0 mode 11.77 MV/m4.96 MV/m 0.82  s, V cath. in 0mode 10 MV/m5.7 MV/m 3.4MHz mode separation 8MHz mode separation From Z.Li, ACD/SLAC Solution : Klystron Pulse shaping

15. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 Conclusion http://www-ssrl.slac.stanford.edu/lcls/prd/1.2-001-r0.pdf Diagnostics were designed to provide Tools for performing correctly emittance compensation 6D characterization of beam at end of injector Diagnostics for degraded beam started Temporal Modulation laser Large emittance => impact on energy spread measurement RF studies L0-1 dual feed: racetrack shape Gun dual feed: racetrack shape Mode0 : problem identified; working on solution

16. Cecile Limborg-Deprey Injector Physicslimborg@slac.stanford.edu October 12 2004 BACK-UP