GPT Simulations Chopper through Booster A Hofler and
GPT Simulations: Chopper through Booster A. Hofler and R. Kazimi July 18, 2019
Model • Gun to Choppers • Field maps -Present CEBAF layout -FAs just upstream and downstream of choppers shifted to new positions away from choppers -Gun: 200 k. V small mushroom 3 D field map -Prebuncher and Buncher from CEBAF model -Booster • 2 -cell • 7 -cell • Chopper exit to Booster -Two layouts -Solenoids • Present CEBAF position • FB from CEBAF model • FD from CEBAF model • Jay’s solenoid design for remainder - Buncher (8. 88 m from gun) - MFA 0 I 06 and MFL 0 I 07 after Buncher - Capture removed • New position - Buncher shifted to midpoint between choppers and 2 -cell of booster (9. 94 m from gun) - MFA 0 I 06 before Buncher - MFL 0 I 07 midway between Buncher and 2 cell • Omitted elements: -15 degree bend -Chopper system -Wiens • Booster exit to entrance of full module -Present CEBAF layout July 18, 2019 2
Optimization • Constraints • 170 u. A beam current -Transmission -Bunchlength at master slit -Kinetic energy sigma • 499 MHz laser frequency • 1000 macroparticles • Prebuncher phase fixed at zero-crossing • 2 pairs of fake correctors -Between gun and first solenoid -Put beam on axis into first solenoid • Population size: 96 • Selected solutions • Seeded with optimization results based on buncher in new position -Beam size < 1. 5 mm -At entrance of full module • Transverse emittance < 1 mm mrad • Kinetic energy sigma < 55 ke. V • Bunchlength < 0. 1 ps • Minimize at the entrance of full module -Bunchlength -Transverse emittance July 18, 2019 -90% transmission (all final solutions) • Particle loss at gun 3
Beam Size (through Booster exit) Prebuncher July 18, 2019 Buncher 2 -cell 7 -cell Prebuncher 4 Buncher 2 -cell 7 -cell
Kinetic Energy (Booster region) 2 -cell July 18, 2019 2 -cell 7 -cell 5 7 -cell
Kinetic Energy (Prebuncher through Buncher region) Prebuncher July 18, 2019 Prebuncher Buncher 6 Buncher
Bunchlength Prebuncher Booster Buncher July 18, 2019 7
Bunchlength (Buncher through Booster) Buncher July 18, 2019 2 -cell Buncher 7 -cell 8 2 -cell 7 -cell
Bunchlength (Full module entrance) July 18, 2019 9
Next steps • Finish post-processing optimization results -Convert RF phases from simulation phases to operational phases (relative to crest or zerocrossing) -Rerun selected solutions with 10000 macroparticles -Check phase spaces • Rerun selected solutions without gun and with appropriate Gaussian distributions to check if -Results change -Beam transmission improves • Check sensitivity of selected solutions • Compare with previous optimization results • Optimization of gun to chopper with Prebuncher shifted to new location July 18, 2019 10
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