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INJECTION STATUS – TOWARDS 144 BUNCHES
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W. Bartmann, C. Bracco, L. Norderhaug-Drosdal, B. Goddard, W. Hofle, D. Jacquet, V. Kain, M. Meddahi, J. Uythoven, D. Valuch, J. Wenninger
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Injection Quality Statuso 24 bunch injection clean:
− Loss maxima from uncaptured beam
− TCDI loss maxima: fill 1646 – 200 bunches filling, 24 bunches per inj
beam 2 3 % maximum, beam 1 8 % maximum
− Beam 1 trajectory not perfect in H, pointing to HiRadMat switch magnet
2TCDIs
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Fine tuning of some thresholds required
o From time to time: low losses “seem” high
o BLMQI.06L2.B2I20 threshold too low
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Threshold of BLMQI.06L2.B2I20
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Transverse losses - observationso Scraping in the SPS needs to be well under control and switched on
− SIS surveillance will come
o Correcting back to reference trajectory works well
− Still more statistics needed for consistency between pilot and nominal intensity corrections
− Need to be able to compare steering settings for 2 users and task in nominal sequence for copy
− Then steering to be done by OP
o For the time being no issues for increasing intensity from transverse losses
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Beam 2:8 bunch injection, no scraping on
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Longitudinal Losseso Larger capture voltage seems to pay off:
− But also some filters changed (e.g. TCTVb)
− Losses at the end of filling: 200 bunch fillings
− …need to check losses on TCLIA/TCTH for beam 1 – losses on D2 on other side are higher than on triplet
o More analysis needs to be done. If possible would like to re-calibrate
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Fill Nr Beam 1 [%] Beam 2 [%]
1645 5 10
1646 10 16
1647 6 8
Max loss in percentage from dump thershold downstream of TDI
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Abort Gap Cleaning @ InjectionAvailable now:
o Sub-Sequence to move abort gap cleaning to injection settings
o Sub-sequence to stop and start abort gap cleaning:
− start abort gap cleaning in prepare for filling sequence
− …and stop before starting the ramp (tune feedback)
o Status:
− Tested with beam: first bucket, NOT with last possible bucket
− Sub-sequences are not part of nominal sequence yet
− MCS checks need to be re-enabled and tested
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Injection Cleaning – not tested with beam
o Injection Cleaning – modus operandi:
− Injection sequencer requests next injection + configures and switches on cleaning
− No injection event: injection cleaning switched off with injection sequencer time-out or internal time-out of injection cleaner
− If injection arriving: automatic switch off cleaning
injection forewarning – details still to be discussed
With beam-in
− At the end of filling: cleaning amplitude and excitation mode set to zero through sequence
o Sequences: prepared, not in nominal sequence Sub-sequence to prepare cleaning before filling
Sub-sequence to disable cleaning after filling
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Injection Cleaning in Injection Sequencer
o Implemented as part of the injection sequencing
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Towards 144 bunch injectionso Quantify effect of TI8 shielding installed during TS (1 hour)o Check aperture TI2 and TI8 after vacuum intervention Shutdown – needed before
injection of >24b (0.5 shift)
o 75 ns spacing, up to 96 bunches (0.5 – 1.5 shifts)− Check losses in the line, oscillations, scraping SPS
− Re-steer if necessary, re-optimise collimators if needed (unlikely...)
o 50 ns spacing, up to 144 bunches (1 – 3 shifts)− Start with 12b
− Check losses in the line, oscillations, scraping SPS
− Re-steer if necessary, hope not to have to re-optimise collimators (can open to +/-5 sig if needed)
− Increase intensity injected in steps (36, 72, 108, 144)
− Checks in SPS extraction, TLs and in LHC at each step (losses, trajectories, oscillations, damping, capture, cleaning, vacuum, ...)
o 25 ns only after experience− Have to obtain more operational experience with up to 144 bunches before increasing
the injected intensity
− Including experience with abort gap and injection gap cleaning
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Beam 2 – 24 bunches
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