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New scraper system: operational aspects

New scraper system: operational aspects. Lene Drøsdal. Current system. Moveable scraper intercept beam Orbit unchanged Scraping is done once per plane at selected time in cycle. New scraper system. Fixed scraper Beam is moved towards scraper by local orbit bump

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New scraper system: operational aspects

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  1. New scraper system: operational aspects LeneDrøsdal

  2. Current system • Moveable scraper intercept beam • Orbit unchanged • Scraping is done once per plane at selected time in cycle LIU-SPS Beam Scraping System Review

  3. New scraper system • Fixed scraper • Beam is moved towards scraper by local orbit bump + The use of a magnetic bump gives better control and flexibility: multiple operations can be done during one cycle - However a magnetic bump implies additional machine protection O. Mete LIU-SPS Beam Scraping System Review

  4. Scraper operations • Removal of transverse tails • LHC: ~3% of intensity removed • Intensity/beam size reduction • HiRadMat • Beam setup • Diagnostics: Scraper beam scan to measure beam profile – requires scraping of full beam New system: Can perform the same operations + diagnostics greatly improved LIU-SPS Beam Scraping System Review

  5. Beam scraping in the LHC • Beam scraping in the LHC in vital for high intensity beams • If the beams are not scraped the beam losses are at the dump threshold for 144 bunches (H+V) and 288 bunches is not possible TCDI @ 5s LIU-SPS Beam Scraping System Review

  6. Scraper scan • Scraper scan: • The scrapers can also be used as a tool to measure the beam profile and tail population • Current system limitations • Only one point can be measured per cycle • The measurement is very slow: ~30 min per plane • Cycle variations (mainly H plane) increase errors of profile measurement Beam centre Non-Gaussian tails LIU-SPS Beam Scraping System Review

  7. Improved diagnostics • A magnetic scraper allows multiple operations within the same cycle  A full scan could be performed during one cycle • The concept was successfully tested during an MD using the extraction bumpers and the TPSG • Could be used as a diagnostics tool LIU-SPS Beam Scraping System Review

  8. Machine protection • Beam losses from scraping • LSS6 is already well equipped with BLMs which will trigger on high losses  Beam dump • A fixed scraper allows better shielding/beam absorbers • TPSG is already in place to protect extraction bump (H) • Same bumpers are used for extraction bump • Need a margin of 680 ms for rise time before extraction • Interlock by limits of allowed operation • Need to protect against bumpers failures • Power supplies and bumper currents need to be monitored • Protection system already exists for bumpers, but need to be modified (circulating beam, multiple checks) LIU-SPS Beam Scraping System Review

  9. EXAMPLE: Bumper failure • Failure of MPSH.62199 • Further studies of failure scenarios still on-going TPSG O. Mete LIU-SPS Beam Scraping System Review

  10. SPS Orbit stability • Over the year large orbit variations was observed in the SPS • In the current system the scrapers are regularly adjusted to maintain correct scraping • Cycle-by-cycle orbit variations are small and can be accepted LIU-SPS Beam Scraping System Review

  11. Orbit stability II • The magnetic bumpers are strong enough to handleorbit variations of: • 8.5 mm in H • 6.0 mm in V • For setup: Might be possible to use the measured orbit to adjust the bump height O. Mete LIU-SPS Beam Scraping System Review

  12. Beam losses • The beam loss pattern are still to be further investigated in simulations • During the MD losses in LSS6 where recorded • Losses have a peak and decays rapidly (low intensity) • Loss peak location depends on the angle (large steps) LIU-SPS Beam Scraping System Review

  13. preparation • A new scraper system requires setup time and testing • Optimum bumper functions • Interlocks to be implemented and tested • New scraper applications are necessary • Standard operational application – should also include checks on allowed operation and correct scraping (diagnostics) • Separate tool for scraper scan • As the scraper is a necessary tool the current system might still be necessary during setup period LIU-SPS Beam Scraping System Review

  14. summary • The new scraper system uses a local orbit bump to move the beam onto a fixed scraper • This system gives increased flexibility • The scraper scans within a cycle could be used as a diagnostics tool • A magnetic bump requires new considerations for machine protection • Beam losses and shielding • Protection of extraction bump and bumper failures  Further studies is on-going • A new system requires setup and commissioning time LIU-SPS Beam Scraping System Review

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