Lene Drøsdal
NEW SCRAPER SYSTEM: OPERATIONAL ASPECTS
LIU-SPS Beam Scraping System Review 2
Moveable scraper intercept beamOrbit unchangedScraping is done once per plane
at selected time in cycle
CURRENT SYSTEM
22.1.2013
LIU-SPS Beam Scraping System Review 3
Fixed scraperBeam 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
NEW SCRAPER SYSTEMO. Mete
22.1.2013
LIU-SPS Beam Scraping System Review 4
Removal of transverse tails LHC: ~3% of intensity
removedIntensity/beam size
reductionHiRadMatBeam setup
Diagnostics: Scraper beam scan to measure beam profile – requires scraping of full beam
SCRAPER OPERATIONS
New system: Can perform the same operations + diagnostics greatly improved22.1.2013
LIU-SPS Beam Scraping System Review 5
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
BEAM SCRAPING IN THE LHC
22.1.2013
TCDI @ 5s
LIU-SPS Beam Scraping System Review 6
Scraper scan:The scrapers can also be used
as a tool to measure the beam profile and tail population
Current system limitationsOnly one point can be measured per cycleThe measurement is very slow: ~30 min per planeCycle variations (mainly H plane) increase errors of profile
measurement
SCRAPER SCAN
Beam centre
Non-Gaussian tails
22.1.2013
LIU-SPS Beam Scraping System Review 7
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
IMPROVED DIAGNOSTICS
22.1.2013
LIU-SPS Beam Scraping System Review 8
Beam losses from scraping LSS6 is already well equipped with BLMs which will trigger on
high losses Beam dumpA fixed scraper allows better shielding/beam absorbersTPSG is already in place to protect extraction bump (H)
Same bumpers are used for extraction bumpNeed a margin of 680 ms for rise time before extraction Interlock by limits of allowed operation
Need to protect against bumpers failuresPower supplies and bumper currents need to be monitoredProtection system already exists for bumpers, but need to be
modified (circulating beam, multiple checks)
MACHINE PROTECTION
22.1.2013
LIU-SPS Beam Scraping System Review 9
EXAMPLE: BUMPER FAILURE
O. Mete
TPSG
Failure of MPSH.62199
Further studies of failure scenarios still on-going22.1.2013
LIU-SPS Beam Scraping System Review 10
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
SPS ORBIT STABILITY
22.1.2013
LIU-SPS Beam Scraping System Review 11
The magnetic bumpers are strong enough to handleorbit variations of:8.5 mm in H6.0 mm in V
For setup: Might be possible to use the measured orbit to adjust the bump height
ORBIT STABILITY II
22.1.2013
O. Mete
LIU-SPS Beam Scraping System Review 12
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)
BEAM LOSSES
22.1.2013
LIU-SPS Beam Scraping System Review 13
A new scraper system requires setup time and testingOptimum 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
PREPARATION
22.1.2013
LIU-SPS Beam Scraping System Review 14
The new scraper system uses a local orbit bump to move the beam onto a fixed scraper
This system gives increased flexibilityThe scraper scans within a cycle could be used as a
diagnostics toolA magnetic bump requires new considerations for
machine protectionBeam losses and shieldingProtection of extraction bump and bumper failures Further studies is on-going
A new system requires setup and commissioning time
SUMMARY
22.1.2013