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Injector RF Gun and L0-1 Design D. H. Dowell, SLAC Lehman Review August 10-12, 2004. Injector Performance Requirements Description of the LCLS Injector RF Gun and Solenoid Design Pulse heating in gun Gun Field Asymmetries Solenoid field asymmetries Gun and L0-1 accelerator section RF design
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Injector RF Gun and L0-1 DesignD. H. Dowell, SLACLehman Review August 10-12, 2004 Injector Performance Requirements Description of the LCLS Injector RF Gun and Solenoid Design Pulse heating in gun Gun Field Asymmetries Solenoid field asymmetries Gun and L0-1 accelerator section RF design Dual feed with racetrack shape Summary
RF Gun Load Lock L0-1 & L0-2 3-m SLAC Sections Gun Diagnostics Laser Heater Transverse RF Cavity DL1 Bend Straight Ahead Spectrometer LCLS Injector Configuration • Progress Since CD2a: • L0-1 Dual Feed RF Design Completed • 120 Hz Gun RF Design Nearly Complete • Laser Heater Added to Injector • =>Replacing SC Wiggler
Dual Feed RF Gun and Solenoid • Request for Information Response from 2 Vendors • Dual Feed/Racetrack Design Corrects RF Fields to Second Order • Solenoid Design Includes Both Dipole and Quadrupole Field Correctors
Localized Pulsed Heating of RF Coupling Port Gun body stress in Pa • Localized heating of the RF coupling port. • The heat flux (watts/m2) is shown for the gun operating at 140 MV/m and 120 Hz. • Total dissipated power is 3676 watts. • The BNL/SLAC/UCLA gun design • has a DT of 137oC/pulse at the port. • The redesigned port gives a DT of • 41oC/pulse. • NLC designs limit DT to 50oC/pulse Analysis by Zenghai Li and Liling Xiao, SLAC/ACD.
Gun Quadrupole RF Field • The gun quadrupole RF field is reduced with racetrack cavity shape • Racetrack design already completed for L0-1 structure Figure complements of Z. Li, SLAC/ACD
Measurements of Gun Solenoid Multipole Fields Gun Solenoid will have Dipole and Quadrupole Correction Coils • Solenoid being designed with both • dipole and quadrupole correcting coils
L0-1 Dual Feed Coupler • Dual feed/racetrack coupler improves • original SLAC design Design by Z. Li, SLAC/ACD
w=24.4000 b=35.95032 t=5.84200 R=3.0861 + + 19.09318 tf=0.78740 36.31233 dc=13.000 Racetrack Dual Feed Eliminates Dipole and Quadrupole Field Perturbations in Coupler Cell • Dual feed eliminates dipole field (amplitude & phase) • Racetrack shape eliminates quadrupole field • Similar approach being used for RF gun Design by Z. Li, SLAC/ACD
Summary and Conclusions • Injector requirements are stringent • Injector parameters require revising the standard RF gun and Slac structure designs • Technical issues: • Pulsed heating of gun coupling ports • Solenoid field asymmetry • RF field asymmetry • Pulsed heating reduced to NLC specification • Solenoid will correct field to second order • Dual feeds and racetrack shape reduce RF field asymmetries