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RF issues, status & plans

RF issues, status & plans. Follow-up after ATOP days March 2009 . Erk Jensen, BE-RF IRF meeting, 2-Sep-09 in preparation of IEFC meeting on 4 th Sept. List of RF issues. Excerpt from https://espace.cern.ch/be-dep/IEFC/Followuplist.html. New issues coming up after ATOP days:.

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RF issues, status & plans

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  1. RF issues, status & plans Follow-up after ATOP days March 2009 Erk Jensen, BE-RF IRF meeting, 2-Sep-09 in preparation of IEFC meeting on 4th Sept.

  2. List of RF issues Excerpt from https://espace.cern.ch/be-dep/IEFC/Followuplist.html New issues coming up after ATOP days: IRF Meeting

  3. Injectors’ RF Meeting • A fortnightly meeting has been initiated by Ed Ciapala and started on May-27th 2009. It is complementary to and alternating with the LHC RF meeting. • Its mandate is to • follow up operational issues concerning RF, • establish communication to and from IEFC, • presentations RF technical subjects. • Technical subjects treated so far: • PSC40 Automatic Tuner Control (P. Maesen) • PSB LLRF renovation (M.E. Angoletta) • PSB Linac4 Interfacing (A. Blas) • RF bypasses (H. Damerau) • SPS Upgrade Project – overview (E. Shaposhnikova) • The IRF meeting was the platform where the aforementioned RF issues are followed up. • http://indico.cern.ch/categoryDisplay.py?categId=2348 IRF Meeting

  4. Renovation SPS 800 MHz system • The issue: • System is necessary, but old &dying (10/16 klystrons broken)! • Status: • Consolidation of existing system: • Power supplies fixed - now 2 systems running, 2 “hot spare” (waveguide switch). • Efforts with industry to repair the Valvoklystrons (CPI). • Tendering for new IOT-based 800 MHz systems: • IT-3624/BE sent out 21-8-09, planned timetable: now: 30th June Delivery of the first Pre-series PA (#1) CERN Site Acceptance Tests 31th March Delivery of the first Series PA (#2 to #5) CERN Site Acceptance Tests 2010 2011 15th March Design Report Review 15th January Programme + every two weeks Progress report 15th June Factory Acceptance Test Of the 1st PA 31st October Acceptance of the first Pre-Series PA 31th January Factory Acceptance Test of the 2nd PA 21st August IT sent what could be then ... 01st October IT closed 15th December Order placed IRF Meeting

  5. Stock of SPS high power tetrodes • The issue(s): • Tubes are consumables! • Of some tubes (YL1530), we had a relatively large (but very old, hence of unknown value) stock of tubes. • This fact together with severe budget limitations had forced us over many years to buy less tubes per year than we consume. • Now the tube stock situation has become critical, just when CNGS (which is very demanding) started in full swing. • If we don’t buy the correct number of tubes regularly, tube manufacturers may decide to stop making them! • For the RS2004, e.g., the lead time for the first 2 tubes is 6 months, then 1 additional month for every batch of 2 tubes. • We have a frame contracts with the 2 tube manufacturers (Thales and Richardson) – they will have to be renewed (or extended) this autumn. IRF Meeting

  6. Stock of SPS high power tetrodes • Status: • Careful statistics done: With 6.25 kh yearly operation, we would need yearly column E, i.e. a budget of column K: • deviations from this to slowly approach I to J (NB: YL1530!) • These numbers (notably column D) are revised regularly. ***) before 2013: 5 per year, from 2013: 21 per year. IRF Meeting

  7. The need for correct yearly maintenance: Transparency shown at ATOP days – no “follow-up”, just a reminder. # of interventionsper week outsidenormal working hours weeks with piquet service • From 2005, limited resources forced us to reduce some maintenance work. • CNGS type beams result in more wear and thus reduce tube-lifetime (16! tubes broken in 2008!) IRF Meeting

  8. SPS Power couplers • Limits (cw, per line): • Amplifier: 750 kW (after combiner),limited by tubes & BW • Coaxial line: 750 kW • Spinner expansion lines: 750 kW • Windows: 800 kW, 1.1 MW, tested “in series”. • Couplers (upgraded 2000...2004) limit: >1.1 MW, tested “in series”. • Connection coupler/cavity: 750 kW, tested 1 MWduring only 10 minutes. Geometry not suitablefor higher powers. • The issues: • One possible conteptually easy upgrade would consist in connecting two lines to one cavity. In this case, the expansion lines, the windows and the connection coupler/cavity would become the bottlenecks. • The connection coupler-cavity is most critical, since in cannot be lab-tested but requires a test-cavity! • Status: • ... not progressed due to other priorities IRF Meeting

  9. PSB C04 water cooling study • The issue: • If the PSB is to pulse with 900 ms, the C04 becomes marginal – 600 ms is impossible. • The conclusion was that even for 900 ms – for reliable operation – an upgrade to water cooling would become necessary • Status: • This was not a priority and no study has been started. IRF Meeting

  10. PSB C02 upgrade necessary? • The issue: • Beam loading: The current limitation of the C02 system would lead to a maximum ΦS of 18°, whereas 22° would be needed for the present cycle. This would indicate an intensity limit of 1.65 E13 per ring; or 6.6 E13 total. • Status: Roadmap of LLRF renovation: • 2009: Operational beams on ring 4 with current h/w + s/w. • 2010-11: Ring 4 equipped with new h/w + s/w • 2012: All rings equipped with new h/w + s/w. • 2012-13: System commissioned for PSB-Linac2 operation. • 2014+: System re-commissioned with Linac4. • The original question, whether PSB C02 needs upgrade for Linac4 or whether new digital LLRF system would suffice, will be addressed once the full potential of the new LLRF system can be evaluated. http://indico.cern.ch/materialDisplay.py?contribId=2&materialId=slides&confId=59488 IRF Meeting

  11. PSB damper upgrade Τ • The issue: • The transverse damper power is not sufficient for operation with Linac 4 • First MD’s showed that 1E13 per ring is the limit of the transverse damper • Status: • MD’s to determine the power necessary for a upgrade of the damper are ongoing – according to A. Blas, results are expected very soon (Sept. 09). IRF Meeting

  12. Hot spare 80 MHz cavity? • The issue: • Tuning for 208Pb54+ and p slightly different • No problem when running Pbor p. • No problem if 3rd cavity is up and running. • No problem if the other species doesn’t require 80 MHz. • Problem only if LHC runs p on Pb! • Status: • Fill LHC sequentially, retune between fillings. • ... requires automatic tuning! • Presented in MSWG on 19-June-09, see https://espace.cern.ch/be-dep/MSWG/Presentations/80MHzions.ppt. IRF Meeting

  13. Tomoscope • The issue: • The Tomoscope is an important operational tool. • The present Tomoscope is based on special hw (scope), which is ageing – some channels started to drop out. • Status: • Since PSB needs all 4 channels, a quick temporary fix was to swap the PS and PSB scopes. • RF+CO (Schokker, Deghaye) are looking already at possible solutions to modernize the software (Java). OASIS scopes, as used in AD & LEIR, cannot be directly adopted due to lack of dynamic range. • To assure operation in the medium term, a second-hand scope of the old type will be purchased. IRF Meeting

  14. PS 40 MHz: Automated tuning • The issue: • The tuning of the 40 MHz cavity slowly drifts, also depending on # of LHC cycles and the beam current. • Automatic (slow) tuning was foreseen from the beginning, but never implemented. • The slow drift required frequent specialist interventions – just for the re-tuning. • Status: • For one of the two cavities (78), a prototype solution has been implemented in June and has since been running smoothly. • A module is missing for a similar solution for cavity 77. M. Vretenar arranged for it to be shipped from Napoli, where it is presently on loan. • A long-term solution, which will be standard across different machines, will be studied by RF-CS. IRF Meeting

  15. PS RF Bypasses • The issue: • On June 10th, a vacuum leak developed in SS52, a 1 Ω resistor was found to be open, traces of arcing. Question: was the RF bypass damage cause or consequence? • Status: • peak power on n-TOF 27 W peak, < 10 W average • The power/voltage specifications of the 1 Ωresistor are 50 W/300 V. • 40 % of the RF bypasses were measuredand found OK. • All this seems consistent and not to be a systematic problem. TOF, 6.1 · 1012ppp 27 W 12 W 9 W 2.5 W H. Damerau, J. Ferreira-Bento IRF Meeting

  16. List of RF issues Issues followed up in IRF meeting, http://indico.cern.ch/categoryDisplay.py?categId=2348 IRF Meeting

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