Modifications to DESY-II M. MintyNov 11, 2003

The DESY-II 7GeV Lepton SynchotronThe DESY-II 7GeV Lepton Synchotron

DORIS finj= 6.25 Hz Einj = 4.5 GeV Nppb = 5 · 109, typical

DORIS finj= 6.25 Hz Einj = 4.5 GeV Nppb = 5 · 109, typical

PIA finj = 50 Hz E = 450 MeV Nppb = (1-2) · 1010

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)

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

beam total number particles injection particleslifetime current of per bunch period per injected (hrs) (mA) bunches in PETRA (s) bunch24 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

Requirements on DESY-II for PETRA-III:Requirements on DESY-II for PETRA-III:

PETRA-III tolerance on total current variation: 0.1 %PETRA-III tolerance on single-bunch current variation: 30 %

injection frequency, initial fill 6.25 Hz wih Nppb=1010

extraction beam energy 6 GeV

extracted beam emittance ≤ 350 nm-rad with p/p = 10-3

top-up mode operation:

improved reliability

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

Extracted beam emitance: ≤ 350 nm-rad with p/p = 10-3

using the present optics:

E (GeV) Δf (kHz) ε (π nm-rad), design p/p (10-3)

7 68 860 1.1

7 0 440 1.2

6 0 325 1.0

no problems in DESY-II expected

(Δf is the presently-used frequency shift for beam loading compensation required for Nppb>1.5·1010)

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.

Top-up mode operation

following the suggestion of the MAC, tests of top-up mode operation at DORIS are underway:

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)

current in DORIS versus timecurrent in DORIS versus time

Tests #3 (6.11.03):

Automated transfers at fixed current into those bunches requiring additional current

work in progress

current in DORIS versus time software interface

(total) intensity stability achieved: ~ 0.5% (compared to 0.1% required), fine-tuning required

Improved reliability

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 systemsreplacement of RF transmitter power feed systemsupgrade of main synchrotron magnet power supplies

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 everyfew months (requiring ~2 hours maximum).

work in progress

Future Plans: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