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Modifications to DESY-II

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  1. Modifications to DESY-II M. Minty Nov 11, 2003

  2. The DESY-II 7GeV Lepton Synchotron DORIS finj= 6.25 Hz Einj = 4.5 GeV Nppb = 5 · 109, typical PIA finj = 50 Hz E = 450 MeV Nppb = (1-2) · 1010 PETRA-II finj=3.125 Hz Einj= 7.0 GeV Nppb = 1.5·1010, (typical) focus of this presentation: requirements of PETRA-III on DESY-II and future plans

  3. Requirements on DESY-II for PETRA-III: • injection frequency, initial fill 6.25 Hz wih Nppb=1010 • extraction beam energy 6 GeV • extracted beam emittance ≤ 350 nm-rad with Dp/p= 10-3 • top-up mode operation: PETRA-III tolerance on total current variation: 0.1 % PETRA-III tolerance on single-bunch current variation: 30 % beam total number particles injection particles lifetime current of per bunch period per injected (hrs) (mA) bunches in PETRA (s) bunch • 100 960 5.0*109 27.0 1.5*109 • 24 200 1920 5.0*109 13.5 1.5*109 • 2 100 40 12.0*1010 7.2 4.8*109 • 1 200 40 24.0*1010 3.6 9.6*109 • improved reliability

  4. Injection frequency, initial fill: frep = 6.25 Hz with Nppb=1010 frep = 6.25 Hz, Nppb = 5 · 109, typical with e+ Nppb = 8 · 109, achieved with e+ Nppb > 1010, typical with e- at E = 4.5 GeV (DORIS-mode) DESY-II transmission efficiency (>90%) seen to be independent of beam energy - same for DORIS-mode with E = 4.5 GeV and for PETRA-mode with E = 7.0 GeV no problems in DESY-II expected Extracted beam energy: E = 6.0 GeV E = 4.5 GeV < E = 6.0 GeV < E = 7.0 GeV (DORIS-mode) PETRA-III (PETRA-mode) no problems in DESY-II expected

  5. Extracted beam emitance: ≤ 350 nm-rad with Dp/p= 10-3 using the present optics: E (GeV)Δf (kHz)ε(π nm-rad), designDp/p (10-3) • 68 860 1.1 • 7 0 440 1.2 • 6 0 325 1.0 (Δf is the presently-used frequency shift for beam loading compensation required for Nppb>1.5·1010) no problems in DESY-II expected An additional factor of ~ 2 reduction in horizontal emittance may be achievable with a higher phase-advance optics. The implications (e.g. costs and geometrical considerations) are being investigated. This possibility does not form part of the design concept for using DESY-II as an injector for PETRA-III.

  6. Top-up mode operation following the suggestion of the MAC, tests of top-up mode operation at DORIS are underway: current in DORIS versus time Tests #1 and #2 (23.10 and 30.10.03): hand-triggered transfers at fixed current into specified bunches (check of timing synchrochronization and of the required “pre-triggers” for the pulsed elements; e.g kickers and septa)

  7. Tests #3 (6.11.03): Automated transfers at fixed current into those bunches requiring additional current software interface current in DORIS versus time (total) intensity stability achieved: ~ 0.5% (compared to 0.1% required), fine-tuning required work in progress

  8. Improved reliability As an injector for DORIS and HERA, the downtime attributable to the DESY-II (and DESY-III) accelerators has been so minimal that thorough study has not been warranted (remedial repairs take place between fills). “Critical access” (as required for beam operations to resume) is seen to be limited to once every few months (requiring ~2 hours maximum). As recommended by the committee, automated compilation of availability statistics including component failures and trend analysis (e.g. out-of-tolerance errors / early identification of changes in system availability) as required for PETRA-III will be implemented next year (an early start). In addition to ongoing accelerator maintenance and modernization, a few major (i.e. high-cost) infrastructural needs have been identified (for ensuring reliable operation of PETRA-III for the next decade): renewal/modernization of water cooling systems replacement of RF transmitter power feed systems upgrade of main synchrotron magnet power supplies work in progress

  9. Future Plans: near-term: integration of new rf amplitude controls further top-up mode tests (including automated selection of desired bunch current) at DORIS at PETRA (?) preparation and demonstration of 6 GeV optics with Δf without Δf with mid-ramp extraction for DORIS resurrect emittance measurements continue investigation of higher phase-advance optics specification and integration of automated availability statistics far-future: hardware improvements mentioned above modernization of rf cavity interlocks replacement of corrector magnet power supplies development of satellite bunch monitor for DESY-II (possibly) separation of vacuum systems DESY-II / DESY-III