LCLS Injector/Diagnostics David H. Dowell, SLAC April 24, 2002 Overview of the LCLS Injector Preliminary Design Description of Major Components Summary LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC

LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC

Injector Layout at Sector 20 Layout Designed Using PARMELA and Elegant Injector Consists of Four Regions: Gun-to-Linac L0 Linacs Matching Section Straight Ahead Tune Up Dump LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC

GTF Gun is Basis for 120 Hz Design 120 Hz Gun Design Includes: RF Probes on both cells Additional cooling RF power feed forward Remote control of cell tuners and cathode plate to compensate for thermo-mechanical detuning Cathode Load Lock J. Weaver/J. Schmerge/ M. Hernandez/D. Reis, SLAC SLAC/BNL/UCLA Collaboration LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC

SLAC/BNL/UCLA Collaboration Thermal Distortions for GTF Gun at 120 Hz, 3 kW Radial Distortion (mil) 0.9 1.2 1.6 1.9 2.3 2.7 1.8 mil ~3.6 MHz Axial Distortion (mil) 1.0 1.7 2.3 3.0 3.6 4.3 1.9 mil ~380 KHz 2.3 mil ~920 KHz Thermal Distribution (degrees F) ~170 deg F ~132 deg F ~122 deg F Optimizing cooling channels, work in progress Highest temperatures on flexible cathode plate Preferentially bakes cathode during operation, cleaning it relative to rest of cavity => Higher QE SLAC/BNL/UCLA Collaboration LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC

Overpowering Gun Reduces Dissipated Power Cavity Voltage vs Time 8 P = 30 MW P = 14 MW klystron 30 14 klystron P = 1.23 kW ave 1.23 3.80 P = 3.80 kW ave 7 E = 140 MV/m cathode 6 5 V (MV) 4 3 2 1 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Time ( m s) J. Schmerge, SLAC LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC

Fast RF Amplitude and Phase Control for 120 Hz Gun By rotating (changing the phase of) two vectors in equal but opposite directions and then combining, the output amplitude can be changed without changing phase. R. Akre, SLAC LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC

Preliminary Design for Cathode Load Lock Load Lock allows efficient cathode replacement Maintains clean cathode during in-vacuum transfer Allows use of reactive cathodes Eliminates need to bake gun after cathode change Allows gun baking w/o cathode plate Better pumping during bake Cleaner gun => Higher RF field (140MV/m) RF Gun Kirby/Collet, SLAC LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC

Diagnostic Locations Measures Determines Gun Spectrometer Gun to Linac Energy Energy Spread E: Gun field DE: Gun balance Electro-Optic Matching Section Electron Bunch Shape Beam Timing SC & RF bunch shape effects E-beam:Laser:RF timing Charge Toroids Everywhere Bunch Charge Transport Beam Position Monitors Non-Intercepting Position Alignment Correlated jitter OTR & YAG Profile Monitors Position Beam Shape Emittance: projected,slice Energy, long phase space Transverse RF Cavity Induces Time-Dependent Kick Longitudinal phase space Slice emittance Wire Scanners ‘Non-intercepting’ RF Cavity Phase Detector Bunch Shape Faraday Cups Straight Ahead Dump Charge Absolute measurement LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC

RF Gun to L0-1 Accelerator Region Laser Penetration Alignment Laser On-Axis Laser Table Load lock not shown M P E B 1 V L RF Gun E A V E 1 Linac Solenoid Gun Solenoid V L M A C V Y 1 - C X F 1 Legend C S CM: Charge Monitor SC: Steering Corrector FC: Faraday Cup BPM: Beam Position Monitor EO: Electro-Optic Gun Spectrometer LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC

Matching Section and Straight Ahead Diagnostics CM3/BPM4/OTR2 EO2: Bunch Shape L0-2 Legend Section Electro-Optic Diagnostic BPM, Beam Position Monitor Non-Intercepting CM, Current Monitor Projected Emittance Measurement OTR, Optical Transition Radiation Screen OTR3,BPM6 Intercepting & "Non-Intercepting" EO, Electro-Optic Longitudinal Phase Space Wire Quadrupole, typ. Slice Emittance Scanners Wire Scanner ("Non-Intercepting") OTR (Intercepting) Scale: Transverse RF Cavity 5.00m. BPM9 OTR6 BPM7/OTR7 Optical Transition BPM10 EO3 Radiation Screen Main Linac Center Line Beam Stopper BPM11/OTR9 OTR10/BPM12/CM6 Tune-up Dump/ Faraday Cup Straight Ahead OTR11/BPM13 Spectrometer Longitudinal Phase Space Slice Emittance Beam Energy Beam Charge LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC

LCLS Injector/Diagnostics Summary Completed Preliminary Injector Design Injector designed with PARMELA and Elegant 120 Hz Gun Further work on gun cooling needed RF heating of cathode may improve QE, lifetime Fast RF control reduces dissipated power factor of 3 RF probes and dynamic tuners in both cells Load Lock Provides fast cathode replacement, no gun baking Allows use of reactive cathodes Improves vacuum and HV operation (140MV/m) Diagnostics Integrated into Injector Design LCLS DOE Review, April 24, 2002 David H. Dowell, SLAC