1 / 10

Longitudinal (in)stability with batch injection

Scheduled Sunday May 8 th , 6:00-10:00. T. Argyropoulos, P. Baudrenghien, T. Bohl, J. E. Muller, T. Mastoridis, G. Papotti, E. Shaposhnikova , D. Valuch, U. Wehrle . Longitudinal (in)stability with batch injection. Presented by P. Baudrenghien BE-RF.

kemal
Download Presentation

Longitudinal (in)stability with batch injection

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. LSWG meeting Scheduled Sunday May 8th, 6:00-10:00 T. Argyropoulos, P. Baudrenghien, T. Bohl, J. E. Muller, T. Mastoridis, G. Papotti, E. Shaposhnikova, D. Valuch, U. Wehrle Longitudinal (in)stability with batch injection Presented by P. Baudrenghien BE-RF

  2. Motivation: Injection transients (dipole?) • Scrubbing run • Observe Bunch-CavSum phase over time • Batches of 36 bunches shown at injection • Very long damping time (~20 minutes) much longer than the decoherence time (7 Hz synchrotron tune spread) • Almost constant over all batches • Does not seem dependent on total beam current Themis Mastoridis LSWG meeting

  3. Motivation: Injection transients (dipole?) 5 last bunches in the last batch after all injections Juan Esteban Muller LSWG meeting

  4. Quadrupole Motion? • b-by-b length • First 5 bunches of each injected train shown • No evidence of quadrupole motion Themis Mastoridis

  5. Step1 0.5 eVs, 6 MV • 450 GeV only. Nominal intensity/bunch, batches 12b, 36b and 72b • Both rings filled identical • Nominal conditions: • SPS: 7.2 MV, 1.5 ns long -> 0.51 eVs • LHC: capture with 6 MV • Fill 1: 12 b (wait 30 min), followed by 36b (wait 10 min) and 36b at closed spacing (wait 10 min). Goal: see the effect of total intensity on the damping time. • Fill 2: 12 b (no wait), followed by 36 b (no wait), followed by 36b at max spacing (wait 20 min). Goal: see the effect on the damping time, of spacing between bunches. • Fill 3: 12 b (no wait), followed by 36b (no wait), followed by 72 b (wait 20 min). Goal: see the effect on the damping time, of nbr bunches/batch • Measurements: • b-by-b phases • b-by-b length • b-by-b longitudinal profile (50 G samples/s) LSWG meeting

  6. Step2 0.7 eVs, 6 MV • 450 GeV only. Nominal intensity/bunch, batches 12b, 36b • Both rings filled identical • Increased emittance: • SPS: 7.2 MV, 1.7 ns long -> 0.7 eVs • LHC: capture with 6 MV • Fill 4:12 b (wait 30 min), followed by 36b (wait 10 min) and 36b at closed (or large - tbd ) spacing (wait 10 min). Goal: see the effect of longitudinal emittance on the damping time • Measurements: • b-by-b phases • b-by-b length • b-by-b longitudinal profile (50 G samples/s) LSWG meeting

  7. Step3 0.7 eVs, 8 MV • 450 GeV only. Nominal intensity/bunch, batches 12b, 36b • Both rings filled identical • Increased emittance and increased LHC voltage: • SPS: 7.2 MV, 1.7 ns long -> 0.7 eVs • LHC: capture with 8 MV • Fill 5:12 b (wait 30 min), followed by 36b (wait 10 min) and 36b at closed (or large - tbd) spacing (wait 10 min). Goal: see the effect of RF voltage on the damping time. • Measurements: • b-by-b phases • b-by-b length • b-by-b longitudinal profile (50 G samples/s) LSWG meeting

  8. Step4 Controlled phase step (momentum kick) 0.5 eVs, 6 MV • 450 GeV only. Nominal intensity/bunch, batches 12b • Both rings filled identical • Nominal long. parameters: • SPS: 7.2 MV, 1.5 ns long -> 0.5 eVs • LHC: capture with 6 MV • Fill 6: • 12 b (no wait), followed by 12b spaced ½ turn apart (wait 10 min for some damping of inj transient) • Give a phase kick by applying a phase modulation at frev in one cavity for ¼ Ts~5 ms (tbd) so that main phase loop does not react (180 deg out of phase displacement for the two batches) • Wait 20 min while measuring • Measurements: • b-by-b phases • b-by-b length • b-by-b longitudinal profile (50 G samples/s) LSWG meeting

  9. Machine Protection issues (Grade A-B ?) • NO change in the transverse plane. • Step 1: below routine operation • Step 2: increased SPS emittance will cause higher capture losses. But less than 100b total. To be monitored with 12b first. Abort Gap Cleaning on. • Step 3: increased SPS emittance AND higher capture voltage -> should lead to less capture loss than 2. • Step 4: small momentum kick but 24b only. LSWG meeting

  10. To be prepared (not LHC RF) • Filling schemes (who?) • Nominal 12b, 36b, 72b • SPS emittance blow-up with 0.5 eVs (nominal) and 0.7 eVs(36b). Can hopefully be prepared in advance. LSWG meeting

More Related