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Beam losses in the CLIC drive beam: specification of acceptable level and how to handle them. ACE 2010 02 04 Michael Jonker. Beam loss detection and Radiation issues. (in the main tunnel). BLM system primary purpose: detection of onset of slow losses.
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Beam losses in the CLIC drive beam: specification of acceptable level and how to handle them ACE 2010 02 04Michael Jonker
Beam loss detection and Radiation issues. (in the main tunnel) BLM system primary purpose: detection of onset of slow losses. Operational beam loss background levels: • Tails on the beam entering the main linac and decelerators • Interaction with residual beam gaz. Loss levels limits • From Beam Physics: 0.1 % main beam, 0.1% each drive train • From Radiation damage over the lifetime of CLIC (1MGy/year see following slides) Hence, these limits will define the required vacuum performance • Resolution at operational background levels 20 % ? Dangerous level of beam loss when 10-2 of DB or 10-4 of MB is lost on an single aperture restriction. (Rough estimate needs further detailed simulations) Extended range for catastrophic (fast) losses: diagnostics only. (i.e. to better understand what happened, if ever something should happen)
Effect of beam in matter • Note:in energy density in cupper for Melting : 400 J g-1, Structural yield 62 J g-1 Material C Al Cu W • LEP Beam (100GeV, 445 nC) • Energy Density @ shower core [J g-1] 0.64 1.68 22 112 • Energy Density @ IB 0.1 mm2 [J g-1] 778 719 624 510 • CLIC Main Pulse (1.5 TeV, 186 nC, @ collimators) • Energy Density @ shower core [J g-1] 3 9 122 614 • Energy Density @ IB 40 mm2[J g-1] 8.3 105 7.7 1056.7 1055.4 1052.2 103 /bunch • CLIC Main Pulse (2.8 GeV, 204 nC @ DR septum) • Energy Density @ shower core [J g-1] 0.01 0.03 0.34 1.6 • Energy Density @ IB 125 mm2 [J g-1] 2.3 105 2.2 1051.8 1051.5 105600 /bunch CLIC Drive Train (2.4 GeV, 24545 nC) Energy Density @ shower core [J g-1] 1.34 3.08 40 187 • Energy Density @ IB 1 mm2 [J g-1] 4293 3964 34442810
Beamlosses (DB 2.4 GeV) 2.4 GeV Lost before QP 1.5 TeV Lost in QP CLIC OMPWG
S. Mallows, T. Otto, CLIC Two-Beam Module Review, September 2009
Permittedfractionalloss model (New model, Drive beam) Based on radiation limits of magnets during 10 years x 6 monthoperation.Regularmagnet design (no rad hard) 2.4 GeV 0.24 GeV CLIC OMPWG
Type of failures • Failures causing slow onset of losses • Magnet system • Vacuum system (performance defined by tolerable operational losses) • Slow drifts (alignment, temperature, …) Next pulse permit and safe by design(2 ms) • Failures causing fast losses (“in-flight” failures) • RF breakdown (effects on the beam under study) • Kicker misfiring (turn around kickers !) • Klystron trips (not applicable for DB) Protection by fixed masks (Impedance?)