1 / 12

Update on AWAKE synchronization with SPS

Update on AWAKE synchronization with SPS. Andy Butterworth ( BE/RF) Wolfgang Hofle, Thomas Bohl ( BE/RF ). Outline. Requirements and constraints Laser m ode locker frequency Synchronization procedure Proposals for frequency generation and signal transmission Conclusions.

deron
Télécharger la présentation

Update on AWAKE synchronization with SPS

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. Update on AWAKE synchronization with SPS Andy Butterworth (BE/RF) Wolfgang Hofle, Thomas Bohl (BE/RF)

  2. Outline • Requirements and constraints • Laser mode locker frequency • Synchronization procedure • Proposals for frequency generation and signal transmission • Conclusions

  3. Requirements • Synchronization between e- gun and laser: few hundred femtoseconds • cf. the plasma period (~ 4 ps) • required for deterministic injection of the witness electron bunch into the plasma wakefields. • Achieved by driving the RF gun with a laser pulse derived from same laser system as used for ionization. • Synchronization between proton beam and laser: < 100ps desirable • cf. proton bunch length (  300ps) Electron bunch (1s ~5ps) Plasma gas proton bunch (1s~300ps) laser pulse (30fs)

  4. Requirements • SPS RF situated in Point 3 next to CCC • Low-level RF electronics in Faraday Cage in BA3 surface building • Synchronization signals to be exchanged on fibres between AWAKE and BA3 • drift/jitter in ps range BA3 ~3km AWAKE

  5. Frequency constraints • Laser requires stable mode-lock frequency reference • between about 50 and 100 MHz • it cannot follow the changes in SPS frequency through the acceleration cycle • SPS and AWAKE cannot be permanently locked together in frequency • SPS must synchronize to AWAKE reference just before extraction of the p+ beam • e- RF gun has limited bandwidth: 2998.5 +/- 1 MHz • and must be locked to the laser frequency (frequency multiple) • SPS RF frequency at extraction = 200.394 +/- 0.001 MHz • adjustment limited by radial beam position • Relationships between frequencies should be feasible to generate in hardware (fairly small integer division/multiplication ratios)

  6. Mode locker frequency choice “Common frequency” used for synchronization Mode locker frequency e- gun frequency multiplier e- gun frequency division/multiplication to get SPS RF frequency reference SPS RF frequency reference 1 pulse every 5 SPS turns Thomas Bohl

  7. Synchronization procedure (1) 1. Rephasing: • Reference signals from AWAKE required by SPS for rephasing: • “Common frequency” fc=frev SPS/5 jitter << 1 SPS RF period (5 ns) • RF frequency reference: 200.394 +/- 0.001 MHz jitter << 10 ps natural beam motion • “Coarse” rephasing: • use the common frequency as a reference. • by manipulating the SPS RF frequency, align the SPS beam with the fc pulse. • precision < 1 SPS RF period (~2 ns) • “Fine” rephasing: • lock the SPS RF frequency to the AWAKE reference RF frequency with a phase-locked loop • precision to O(10 ps) ? 2. Extraction timing: • 1 proton bunch every ~30 seconds: extract beam to coincide with the laser pulse • extraction takes place at variable time in cycle • needed in order to synchronize with the laser pulse: • frep laser pulse repetition frequency (~10 Hz) jitter << 12 ns laser rep.

  8. Synchronization procedure (2) • Start flat-top, launch rephasing, wait 500msfor rephasing to be finished • Wait for next frep pulse, arm counters etc. for next pulse • Next frep pulse sends external event to central timing (for extraction forewarnings) and starts fine timing for bunch rotation and extraction SPS cycle: Injection Ramp Flat-top Magnetic field (beam energy)

  9. Synchronization signals CERN BE/RF RF reference frequency (+/- 1 kHz) 1 pulse every 5 SPS turns laser pulse picker 10Mhz reference for synchronization of instrumentation etc.

  10. Proposal 1 CERN BE/RF Frequency generation provide by Amplitude Stabilized fibre links developed by CERN BE/RF

  11. Proposal 2 CERN BE/RF Fibre link Stabilized fibre link provided by Menlo Transport only 88 MHz (+ 10 Hz modulation?) Frequency generation done on SPS side, developed by CERN BE/RF

  12. Conclusions • A scheme for SPS synchronisation with AWAKE has been developed • similar to technique used for filling LHC • synchronization signals have been specified • timing scheme for synchronization and extraction has been proposed • The laser mode locker frequency has been chosen and included in the specifications given to the laser supplier • Key components are under discussion with manufacturers: • frequency generation chain to synchronize laser, RF gun and SPS RF • fibre signal transmission between SPS P4 and SPS RF

More Related