Crab Cavities: Speed of Voltage Change (a machine protection issue for LHC [and SPS] )
LHC Crab Cavities – some outcomes from the Chicago meeting in December 2013
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Transcript of LHC Crab Cavities – some outcomes from the Chicago meeting in December 2013
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LHC Crab Cavities – some outcomes from the Chicago meeting in
December 2013
Ofelia Capatina
CCTC #4OC, 17/Jan/2013 1
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• https://indico.cern.ch/conferenceOtherViews.py?confId=136807&view=standard
General
OC, 17/Jan/2013 CCTC #4 2
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• 4-ROD
Helium tank and Tuner concepts
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• RF Dipole
Helium tank and Tuner concepts
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• QWR
Helium tank and Tuner concepts
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Design Approach – Cryomodule Schematic
Shrikant Pattalwar Hi-Lumi Crab Cavity Engineering Meeting Dec 13-14, 2012 Fermi Lab
TWO PHASE LINE
60 K RETURN40 K FORWARD
4K (LHe) SUPPLY
2K (GHe) RETURN4K GHe RETURN
THERMAL SHIELD 40K TO 60K
5K THERMAL INTERCEPTS
4K P
RE-C
OO
L
2K HEX and a valve box could be a part of the module ??
Magnetic shieldOuter Vacuum Chamber
Shrikant Pattalwar
LHC Crab Cavity Cryostat, 14 Dec 2012 6
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Design Approach – Conceptual Model
Shrikant Pattalwar Hi-Lumi Crab Cavity Engineering Meeting Dec 13-14, 2012 Fermi Lab
1000mm2160mm
1000
mm
Triple tube cavity support system
High order mode coupler
Low order mode coupler
RF input coupler
SPS by-pass line
413mm
420mm
194 mm
Shrikant Pattalwar
LHC Crab Cavity Cryostat, 14 Dec 2012 7
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• SPS test imposes already many constraints in itself - concepts for equipped cavities may be different between LHC and SPS
• Some basic choices done for SPS tests during this workshop• 2 (identical) cavities in a cryomodule• 3 different cryomodules • FPC recommended (not an obligation) from the top
and vertical of the cavity (62 mm OD) – see Eric’s talk• All cryo interfaces from top• 40 liters helium recommended; max. 100 liters –
however helium inventory will not be a stopping point
Basic choices at Chicago
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• SPS test• Available space requirement
• Beam pipe distance 500 mm • Is tests at 4.5 K is not the baseline but
could remain a posibility• Design for 2 K • Check design for 4.5 K also
• Yes we keep the dummy beam pipe at 194mm
Basic choices at Chicago
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• Tuning ranges• Operation frequencies and detuning
• 60 kHz – slow tuning• 1.5 kHz – fast (de)tuning
• Δf induced by Lorentz detuning and operating pressure
• Ensure stability / pressure fluctuation for 400Hz BW
Tuning
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Parameter Units LHC SPSFrequency MHz 400.79 400.73 400.78 400.79Δf kHz 0 -58.2 -12.2 -2.4Bandwidth Hz 400 400 400 400
Fast and slow TBD
Cavity specific
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• Helium tank• Tank material not imposed; however titanium
involves• More complex interfaces • Not covered by the Harmonised European
Standards => might require additional test • Stainless steel flanges for beam pipe interface• Interfaces to be harmonized in cryomodule –
seems to go away more and more => dedicated cryomodule for each cavity
Helium tank
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• We can use the adjacent beam pipe to reinforce cavity
• We can have the adjacent beam pipe in the liquid helium
Helium tank
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• Common boundary conditions will be formalized in January 2013
• Next common discussion in February 2013
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