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Interleaved Filling Possibilities. Interleaved Filling Possibilities V. Kain , K. Cornelis, J. Wenninger. Introduction Filling the LHC – nominal concept How will we do it? What is the problem? Cycles for next year Summary. Introduction – Filling the LHC (SPS point of view).

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Interleaved filling possibilities
Interleaved Filling Possibilities

Interleaved Filling Possibilities

V. Kain, K. Cornelis, J. Wenninger

  • Introduction

  • Filling the LHC – nominal concept

  • How will we do it?

  • What is the problem?

  • Cycles for next year

  • Summary

Oct 9, 2007


Introduction filling the lhc sps point of view
Introduction – Filling the LHC (SPS point of view)

  • 2 different SPS extraction for the 2 LHC rings:

    • LSS6 → TI 2 → beam 1

    • LSS4 → TI 8 → beam 2

  • Nominal filling: 12 injections per ring

  • Can we fill the LHC in an interleaved way?

Oct 9, 2007


Interleaved filling possibilities

YES…

Can we do it easily, efficiently…?

Oct 9, 2007


Introduction sps extractions
Introduction - SPS extractions

  • Large horizontal bump (> 35 mm)

  • Fast extraction kickers (~ 50 kV in LSS4, ~ 30 kV in LSS6)

  • Extraction septa

Example: LSS4

Oct 9, 2007


Filling the lhc ideal world nominal concept
Filling the LHC – Ideal World - Nominal Concept

  • The plan (and reality) is

    • The Central Timing System controls the production of the LHC beams in the Injector chain via the CBCM (Central Beam and Cycle Manager)

    • Beams are associated with “users” in the different accelerators to define the magnetic cycles and destinations

    • Static destinations/ dynamic destinations

      • E.g.: LHC beam: static destination: SPS dump, dynamic destination: set on the fly (TI 8 dump, TI 2 dump, TI 8/LHC2, TI 2/ LHC1)

      • Destinations: TI 8/ LHC2, TI 2/LHC1 can only be set by the LHC sequencer

      • Sequencer requests: beam type (number of batches), target RF bucket, ring

  • Hence the required supercycles in the SPS

    • Supercycle: LHC nominal (~ 20 s)

    • Supercycle: FT + 3 CNGS + pilot (~ 43 s)

    • Supercycle: pilot (~ 8 s)

Oct 9, 2007


But we can t do it like this yet
But…we can’t do it like this yet…

  • The SPS power converter control (mugef) is run by the ROCS software

    • The mugefs do not “understand” destination

  • The extraction kickers understand destination

  • Could always pulse both lines plus both extractions….and same scenario as before

     expensive

    • safety issue: the bumps in the SPS

      • in case of problems during extraction (kicker problems,…) risk to damage both extraction channels

  • The ROCS system will go FESA or something similar one day

    • …but not for next year!!!!!!!!

Oct 9, 2007


How will we do it how did we do it
How will we do it? How did we do it?

  • Instead of one LHC user per SPS supercycle and two destinations…

  • 2 LHC users per SPS supercycle (with different destinations)

    • = two LHC cycles per SPS supercycle

Example: this year’s

interleaved extractions

to TT40 and TT60:

2 LHC pilot cycles in the

SPS supercycle. 2 users,

one for LSS4, one for LSS6.

Each transfer line pulsed only

once per SC.

Total length: 16.8 s

Oct 9, 2007


So what is the problem 1
So, what is the problem? (1)

  • Same supercycle, filling only one ring, takes 2 x as long…

  • Could be overcome by changing supercycle in case:

Example: supercycle for

interleaved nominal filling.

Total length: 43.2 s

SFTPRO + pilot

Etc.

LHC nominal

Pilot interleaved

Oct 9, 2007


So what is the problem 2
So, what is the problem? (2)

  • All supercycles have to be ready

    • The timing sequences need to be prepared as well (also for different beam types)

  • To be really efficient: all supercycles should be resident in the hardware

  • BUT….

    • there are not enough users

      • 24

        • already three for CNGS, three for coast, pstart/pstop, SFTPRO,…

    • the ROCS do not have enough memory

  • Change supercyle if cycles resident:

    • 1 – 2 minutes

  • Change supercycle if cycles not resident:

    • up to half an hour

Oct 9, 2007


Cycles for next year
Cycles for next year…

  • For next year we can live with the current situation

  • Always resident:

    • Supercycle: FT + 3 CNGS + LHC pilot (length ~ 43 s )…or similar

      • parallel MD cycle ?!?!?

    • Supercycle: LHC pilot(length ~ 8 s)

      • fine for single injections from PS: pilot, one bunch, 4 bunches, 12 bunches, 48 bunches, 72 bunches

      • Low intensity (up to 12 bunches) interleaved: both lines + bumps pulsing

  • Other cycles which will be there, but (probably) not resident:

    • Supercycle: LHC nominal

    • Supercycle: LHC nominal + LHC nominal

Oct 9, 2007


Prospect and proposal
Prospect and proposal

  • ROCS will migrate in shutdown 2008/2009

    • next generation software will understand destination

  • We would like to have more users 24 + > 8

    • despite memory limitation in the ROCS

      • Clean up the functions for the corrector magnets

Oct 9, 2007


Solution for next year
Solution for next year…

About 1.3 x 1013 protons per extraction

Oct 9, 2007


Summary
Summary

  • We can fill the LHC in an interleaved way.

  • Current limitations for efficient and flexible filling of the LHC:

    • SPS mugefs (mainly the extraction bumpers)

  • Solution:

    • Migration of ROCS to FESA or similar (will come)

    • More users, at least 8 more

Oct 9, 2007


Additional complexity no showstopper
Additional complexity – no showstopper

  • LSS4: LHC and CNGS extraction

    • MBIs: main dipole chain in TI 8/ CNGS…same power converter

    • Electronic switch: current below 1 % of nominal during beam out

  • Same thing for the MBSG (switch magnet between CNGS and TI 8)

  • Separate beam transfer needs to be defined for TT40

    • Otherwise cannot have CNGS and LHCbeam 2 transfer in the same supercycle

  • CTIMs to be managed by LSA

Oct 9, 2007