Status of the Simulations on Photo Injector Optimization for Low Charges Yauhen Kot BD Meeting,

Preliminary results work is not accomplished yet…

Optimization Code for the Photo Injector by M. Krasilnikov

BoosterACC13,9GHz Gun FLASH Photo Injector Booster phase is fixed Same gradient at booster and ACC1

+ Bucking coil peak field E z1 (z=0)=45MV/m Optimization Code for FLASH Photo Injector

efld.dat FLASHgun_p12.dat Tuning parameters for efld Beam sizeXYrms SolenoidMaxB(1) Bucking Coil MaxB(2) GunMaxE(1)45.00 Phi(1) BoosterMaxE(2)40.12 Phi(2) Tuning parameters for FLASHgun_p12 Beam sizeXYrms SolenoidMaxB(1) Bucking Coil MaxB(2) GunMaxE(1)45.00 Phi(1) BoosterMaxE(2)40.12 Phi(2) horvert   reduced   horvert   reduced   Field Files for the Gun Slightly different files but big consequencies

efld FLASHgun_p12 xx yy xx yy xx yy xx yy   reduced   reduced Calculated with best parameters for efld.dat. Comparison

Tuning Parameters ChargeXYrmsGun Phase, Phi(1) 1.1ps3.3ps4.4ps1.1ps3.3ps4.4ps ChargeBooster gradient, MaxE(2)Booster phase, Phi(2) 1.1ps3.3ps4.4ps1.1ps3.3ps4.4ps ChargeSolenoid MaxB(1)Bucking Coil, MaxB(2) 1.1ps3.3ps4.4ps1.1ps3.3ps4.4ps Field File efld.dat - Booster gradient and phase were considered as parameters to be optimized - Best value for booster gradient was found in the near of the desired 40.12MeV almost in all cases - Booster Phase seems not to affect the emittance significantly - Results after ~50 Iterations with Optimization Code with 2000 particles

Results after Booster at s=9.0m ChargeEmittanceBunch length 1.1ps3.3ps4.4ps1.1ps3.3ps4.4ps ChargeBetaAlpha 1.1ps3.3ps4.4ps1.1ps3.3ps4.4ps ChargeEnergy rmsmomentum 1.1ps3.3ps4.4ps1.1ps3.3ps4.4ps Field File efld.dat - Run with particles with the best values from the optimization code

Bunch Shape for 4.4ps and 3.3ps 20pC, pulse length = 4,4ps 100pC, pulse length = 4,4ps 40pC, pulse length = 4,4 ps 40pC, pulse length = 3,3 ps100pC, pulse length = 3,3ps 20pC, pulse length = 3,3ps Optimization procedure was cut after iterations  possibly not enough to find really best values

Slice Energy Emittance and Slice Energy Spread for 4.4ps and 3.3ps

Convergency: Slice Energy Spread and Slice Emittance Q=100pC Pulse Shape: Gaussian  =4.4ps N, x10 3 Mesh  m  mm  rms,mm E rms, keV  m  20015x x x x Main parameters after booster at s=9.00m

Sensitivity Test: Solenoid 100pC, 4.4ps I soll MaxB(1)  Assume I soll (optimum)=300.0A - The accuracy of 0.1A of the set point of the solenoid current Should be sufficient to control the emittance - But big difference in the optics functions…

I soll MaxB(2)    Assume I soll (optimum)=16.0A Sensitivity Test: Bucking Coil 100pC, 4.4ps

Solenoid Test: Bunch Shape Still to clear up: if the emittance increase at higher solenoid field occurs only due to the tails of the bunch…

Bucking Coil Test: Bunch Shape

Summary Many open questions yet…