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