LHC Crab Cavities – some outcomes from the Chicago meeting in

December 2013

Ofelia Capatina

CCTC #4OC, 17/Jan/2013 1

• https://indico.cern.ch/conferenceOtherViews.py?confId=136807&view=standard

General

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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

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

• 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

• 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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