MDs on beam induced heat loads in the
MDs on beam induced heat loads in the arcs • List presented by L. Tavian at the LMC, corresponding MD requests have been created and detailed a bit further in the following
Go od c for and MD idat e 1 MD 3296: Impact of spool-piece correctors on heat loads
MD 3296: Impact of spool-piece correctors on heat loads Time required: 8 h - beam phase: injection • Goal: investigate impact of spool-piece correctors on arc heat loads (as some indications point to heating concentrated at the interconnections) • Procedure in short: • Setup the machine with pilots at injection with the RCS RCO and RCD circuits switched off in one arc. o In particular chromaticity and coupling will have to be corrected • In these conditions, fill the machine using the operational 25 ns beam (BCMS) and acquire heat load data • Repeat the procedure with a high-load and a low-load arc • Requires non-operational beam from injectors? : no
Go od c for and MD idat e 1 MD 3300: Heat load measurements with different bunch intensity
MD 3300: Heat load with different bunch intensity Time required: 8 h + 8 h - beam phase: injection + flat-top • Goal: further investigate the dependence of the heat load on the bunch intensity • Short procedure: • Fill the LHC at injection with 25 ns beams (ideally full beam) with different bunch intensity (in the range 0. 3 -1. 2 e 11 p/bunch) o Check behavior of interlocked BPMs and orbit feedback in the low-intensity range • For two selected points (possibly 0. 3 and 0. 7 p/bunch) acquire measurements also at flat top • Requires non-operational beam from injectors? : yes • 3 x 48 bpi, 0. 9 e 11 p/bunch (BCMS) • 3 x 48 bpi, 0. 3 -0. 7 e 11 p/bunch (standard)
MD 3298: Heat loads with different bunch length
MD 3298: Heat load with different bunch length Time required: 4 h - beam phase: injection • Goal: further investigate the dependence of the heat load on the bunch length • Short procedure: • With full operational 25 ns beams, change the bunch length by trimming the RF voltage and/or applying controlled longitudinal blow-up. • Requires non-operational beam from injectors? : no • Requires RF support
MD 3297: Heat load measurements with orbit bumps in the arcs
MD 3297: Heat load with orbit bumps in the arcs Time required: 4 h - beam phase: injection • Goal: further investigate the dependence of the heat loads on the transverse beam position • Short procedure: • With full operational 25 ns beams, perform orbit bumps in selected arc cells and measure the impact on the heat loads. • SIS orbit interlocks will have to be masked if possible • Requires non-operational beam from injectors? : no
MD 3295: Heat load measurements with a single circulating beam
MD 3295: Heat load with a single circulating beam • Goal: investigate asymmetries in heat load between B 1 and B 2 • Short procedure: • Take a single 25 ns beam to flat-top and acquire heat load data • SIS orbit interlocks will have to be masked if possible • Requires non-operational beam from injectors? : no
MD 2484: Heat load studies high intensity 8 b+4 e beams
MD 2484: Electron cloud studies 8 b+4 e beams • Filling pattern designed to suppress the e-cloud build-up (lower thresholds expected from simulations) Confirmed experimentally in the LHC in 2015 Included in the HL-LHC TDR as backup scenario in case issues with e-cloud Up to ~1900 b. in the LHC “ 8 b+4 e” beam Standard 25 ns beam Dipoles (instrumented cells in S 45) Average Impedance+synch. rad
MD 2484: Electron cloud studies 8 b+4 e beams • Filling pattern designed to suppress the e-cloud build-up (lower thresholds expected from simulations) Confirmed experimentally in the LHC in 2015 Included in the HL-LHC TDR as backup scenario in case issues with e-cloud • Tests in 2015 were carried out with nominal bunch intensity while for HL-LHC we assume >2 x 1011 p/bunch important to check that the e-cloud suppression does not degrade with bunch intensity • 8 b+4 e trains with bunch intensities higher than nominal (~1. 7 e 11 p/bunch) already be available single train tested in 2017 • We propose to perform a fill with several bunch trains (ideally with full machine) to verify the e-cloud suppression • Requirements: o Operational machine cycle, with changes necessary to handle larger bunch intensity, e. g. ADT, octupoles (setup could be shared with high pile-up test) o Flat top is enough for e-cloud measurements, but going to collisions could be useful for other studies (luminosity evolution, beam-beam…) o 2 h a high energy • As discusses last year this will require an intensity ramp-up
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