1 / 6

Changes w.r.t LBL simulations

Changes w.r.t LBL simulations. Set gun phase for minimum energy spread S et on-crest phases for all cavities after buncher Turned off 2 nd cavity (~5MV/m amplitude for LBL versions for 2 nd cavity) Optimized cavity field amplitude & solenoids

shiloh
Download Presentation

Changes w.r.t LBL simulations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Changes w.r.t LBL simulations • Set gun phase for minimum energy spread • Set on-crest phases for all cavities after buncher • Turned off 2nd cavity (~5MV/m amplitude for LBL versions for 2nd cavity) • Optimized cavity field amplitude & solenoids • Emittance improved ~10% - LBL simulations have been good in general. Feng Zhou, 12/18/2013

  2. Independent control for 1st 9 cells (APEX gun, 300pC) • Slice emittance & bunch shape stay similar. • More knobs help to improve the slice matching, which improve projected emittance ~20%. • Further look into dc gun as well Same phase/amp different phase/amp

  3. Concerns for charge production • Current laser sizes need 2-3 times additional laser energy for the required charge as they work at the space charge limited charge production region. • Does laser energy have enough headroom?

  4. Cornell vs. LBL injector layout Cornell, Ez Cornell, Bz • 300pC Cornell: • Laser pulse 28 ps • Laser size 3mm • Thermal emittance 0.48um/mm-rms APEX, Ez APEX, Bz • 300pC APEX: • Laser pulse 56 ps • Laser size 1.2mm • Thermal emittance 1um/mm-rms

  5. Observations from Cornell simulations • Reproduced Cornell results but found the bunch shapes are asymmetry from the charge 50pC to 500pC • Asymmetry may be improved after tweaking the phases but most likely it will be similar to APEX in the end.

  6. Summary • Independent control for 1st 9 cells: • For APEX: only improve projected emittace 20%. Slice emittance/bunch shape stays similar. • For Cornell dc gun: is under study. • Current design with APEX gun requires extra 2-3 times laser energy as charge production is in space charge limited regime. • Have to enlarge laser size thus sacrifice emittance if laser is not capable to produce enough energy-headroom • A little more simulations for Cornell DC gun are needed to improve the asymmetry bunch.

More Related