Cryostat Issues for SPS Crab Cavity Run: Envelopes and Interfaces - - PowerPoint PPT Presentation

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Cryostat Issues for SPS Crab Cavity Run: Envelopes and Interfaces - - PowerPoint PPT Presentation

Dec 22, 2023 210 likes •514 views

Cryostat Issues for SPS Crab Cavity Run: Envelopes and Interfaces Alick Macpherson RF Group CERN Fermilab cryostat meeting - 30th May 2013 Acknowledgments Philippe Baudrenghien, Krzysztof Brodzinski, Rama Calaga, Ofelia Capatina, Frederic

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SLIDE 1

Cryostat Issues for SPS Crab Cavity Run: Envelopes and Interfaces

Alick Macpherson RF Group CERN Fermilab cryostat meeting - 30th May 2013

Acknowledgments Philippe Baudrenghien, Krzysztof Brodzinski, Rama Calaga, Ofelia Capatina, Frederic Galleazzi, Erk Jensen, Eric Montesinos, Vittorio Parma, Rogelio Tomas, Giovanna Vandoni

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SLIDE 2

SPS Run: Overview of Constraints on Cryostat design

  • Cryo module must contain 2 cavities
  • Cryomodule must be out of beam line when cavities not under test
  • Remote control of movement essential
  • Module to be moved while cold and full of LHe
  • Alignment and positioning:
  • Accurate positioning wrt the closed orbit beam is essential
  • Question: Is active alignment within the cryostat required/feasible?
  • Cryo module should be exchangeable in an SPS technical stop
  • Technical stop = 3 days => common envelopes and common interfaces
  • Foresee both horizontal and vertical crabbing could be tested:
  • Possibility of more than one cryostat tested in SPS Run
  • Designs must have common connection interfaces (type + position)

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SLIDE 3

Infrastructure constraints on location

  • Cryogenics: Can’t guarantee 24/7 cryo operation in SPS
  • Cryo module: must be able to cycle it out of the beam line
  • Space required for “out of beam position”
  • Horizontal move (standard) => SPS alcove (not possible in tunnel)
  • Vertical move: Very very challenging, space/clearance an issue
  • Interfaces
  • Rigid connection between tetrode and cryomodule
  • Rigid connection between cryo 2K expansion box and cryomodule
  • RF-Power and LLRF
  • Tetrode+ circulator as close as possible to cryomodule
  • Space required => location restricted to an alcove

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SLIDE 4

Infrastructure constraints on location

  • Cryogenics: Can’t guarantee 24/7 cryo operation in SPS
  • Cryo module: must be able to cycle it out of the beam line
  • Space required for “out of beam position”
  • Horizontal move (standard) => SPS alcove (not possible in tunnel)
  • Vertical move: Very very challenging, space/clearance an issue
  • Interfaces
  • Rigid connection between tetrode and cryomodule
  • Rigid connection between cryo 2K expansion box and cryomodule
  • RF-Power and LLRF
  • Tetrode+ circulator as close as possible to cryomodule
  • Space required => location restricted to an alcove

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SPS: Cryo module location needs space for Y-chamber and RF power => location must be in an SPS alcove (or similar)

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SLIDE 5

SPS: Space in the tunnel

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SLIDE 6

SPS: Space in the Alcove

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SLIDE 7

SPS location: LSS4

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LLRF

ECX4( 35m)

CC

SPS: LSS4 alcove of BA4 is the only location that is feasible /available

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SLIDE 8

SPS location: LSS4

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LLRF

ECX4( 35m)

CC

SPS: LSS4 alcove of BA4 is the only location that is feasible /available

E l e c t r i c a l ¡ e q u i p m e n t

TCF20 Pump

Buffer

Heater SM

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SLIDE 9

Issues with the SPS LSS4 Location

  • SPS Extraction bump prohibits CC in beam when filling LHC
  • CCs in beam: Blocks LHC filling. Aperture bottleneck for normal SPS operation

=> Y-Chamber needed so cavities can be bypassed when not under test

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20 40 60 80 100 120 20 40 60 80 100 120 3977 3985 3993 4001 4009 4017 4025 4033 4041 4049 4057 4065 x (mm) s (m) x (mm)

Diluter + septa Circulating beam Coldex location

x (mm) s (m) x (mm)

Extracted beam Circulating beam Coldex location

Crab

SPS LSS4: LHC Extraction bump (Q20 optics)

Location is not ideal: Aperture bottleneck + must interlock on CC + LHC filling

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SLIDE 10

Movement of Crab cavities in/out of beamline

SPS operation must be independent of crab cavity operational availability => Crab Cavity cryomodule switchable from in-beam to out-of-beam position

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Dummy LHC Beam Pipe

SPS Outside SPS Inside

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SLIDE 11

Movement of Crab cavities in/out of beamline

  • Crab Cavity module switchable from in-beam to out-of-beam position
  • Y-chamber movement: reproducible 51cm movement in < 30min
  • Must be remote controlled (ie no access required) and take
  • Safety incorporated into support structure design
  • Mechanical movement with helium vessels, cryo-lines etc at 2K

SPS operation must be independent of crab cavity operational availability => Crab Cavity cryomodule switchable from in-beam to out-of-beam position

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Dummy LHC Beam Pipe

SPS Outside SPS Inside

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SLIDE 12

Crab Cavity Integration envelope

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510 mm

Dummy LHC Beam Pipe

3000 mm

SPS Outside SPS Inside

Description Distance [mm] Envelope z-length 3000 Cavity axis to inner edge of Envelope volume 420 Cavity axis to outer edge of Envelope volume 680* Cavity axis to bottom of Envelope volume (top of support table) 700* Cavity axis to top of Envelope volume 800 Cavity axis to SPS floor 1200 Cavity axis to By-pass axis 510 Diameter of bypass beam line 159 Diameter of cavity aperture 84 Dummy beam pipe outer diameter (HL-LHC BP in Q4-D2 region) ~100 Cavity axis to dummy beam pipe axis 194

* = possible to increase

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SLIDE 13

Crab Cavity Integration envelope

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RF Amplifiers & Circulators Support Table Cryomodule Envelope Crab Cavity Support Infrastructure

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SLIDE 14

Crab Cavity Integration envelope

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RF Amplifiers & Circulators Support Table Cryomodule Envelope Crab Cavity Support Infrastructure

800 mm

External connections need to be inside in envelope as have to respect table movement constraints => integration interfaces ..... not a lot of space

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SLIDE 15

Space in LSS4 - Physical Obstacles

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SLIDE 16

Space in LSS4 - Physical Obstacles

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SLIDE 17

Integration Envelope Questions

  • Dummy Beam Pipe: CC Axis-to-Dummy BP axis distance = 194 mm
  • Can be at any location (horizontal, vertical etc) wrt CC axis
  • Exception: UK-4Rod has FPC connection to CC on horizon
  • Question 1: Can we move location of dummy Beam pipe?

=> we gain space between CC and by-pass, makes things easier.

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SPS Outside SPS Inside

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SLIDE 18

Integration Envelope Questions

  • Dummy Beam Pipe: CC Axis-to-Dummy BP axis distance = 194 mm
  • Can be at any location (horizontal, vertical etc) wrt CC axis
  • Exception: UK-4Rod has FPC connection to CC on horizon
  • Question 1: Can we move location of dummy Beam pipe?

=> we gain space between CC and by-pass, makes things easier.

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SPS Outside SPS Inside

Question 2: Can distance from CC axis to the inside edge of envelope be reduced from 420mm to 255 mm?

  • If so we can use existing Y-chamber
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SLIDE 19

Integration Envelope Issues

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SPS Outside SPS Inside

  • CC Envelope: Physical envelope of space available
  • Includes cryo module and connections (up to integration interfaces)
  • Connections from all sides except inside face
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SLIDE 20

Integration Envelope Issues

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SPS Outside SPS Inside

helium ¡tank crab ¡cavity common ¡pumping ¡collector thermal ¡screen ¡at ¡~80 ¡K cryostat ¡interface CWT Power ¡coupler ¡intercept CWT

SKETCH

LT PT EH TT EH TT LT

  • Integration interfaces at

envelope need to be clearly defined

  • Must take connections

into account

  • Input to specifications

Integration interfaces

  • CC Envelope: Physical envelope of space available
  • Includes cryo module and connections (up to integration interfaces)
  • Connections from all sides except inside face
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SLIDE 21

Alignment Tolerances

  • Based on modeling Crab Cavities with multipoles up to octupole order
  • Transverse misalignment tolerances [ TMT]
  • TMT defined as a 1 sigma reduction of dynamic aperture.
  • TMT = 0.7 mm for each cavity
  • Applies to both planes: different crossing schemes for IR1 & IR5
  • Tilt of the cavity wrt longitudinal cryostat axis < 1 mrad
  • Based on luminosity loss, closed orbit deformation, tune modulation
  • Transverse rotation of individual cavities inside cryostat < 5 mrad (~0.3 deg)
  • Based on effects of parasitic crossing angle in the non-crossing plane
  • Assume

electro-magnetic centre axis of cavity = geometrical longitudinal axis of cavity = longitudinal cryostat axis = geometric center of the beampipe

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SLIDE 22

Positioning of Cryomodule

  • RF amplifier TX power vs. QEXT: (400 MHz - 50 kW SPS Tetrode)

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Blue trace => 1 mm offset Red Trace => 0 mm offset

50 kW

Acceptable transverse

  • ffset of beam wrt cavity
  • f O(1mm)
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SLIDE 23

Positioning of Cryomodule

  • RF amplifier TX power vs. QEXT: (400 MHz - 50 kW SPS Tetrode)

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Blue trace => 1 mm offset Red Trace => 0 mm offset

50 kW

20 40 60 80 100 120 20 40 60 80 100 120 3977 3985 3993 4001 4009 4017 4025 4033 4041 4049 4057 4065 x (mm) s (m) x (mm)

Diluter + septa Circulating beam Coldex location

x (mm) s (m) x (mm)

Extracted beam Circulating beam Coldex location

Crab Cavity

SPS LSS4: LHC Extraction bump (Q20 optics)

Circulating beam is offset significantly wrt to nominal beam axis Acceptable transverse

  • ffset of beam wrt cavity
  • f O(1mm)
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SLIDE 24

Positioning of Cryomodule

  • RF amplifier TX power vs. QEXT: (400 MHz - 50 kW SPS Tetrode)

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Blue trace => 1 mm offset Red Trace => 0 mm offset

50 kW

20 40 60 80 100 120 20 40 60 80 100 120 3977 3985 3993 4001 4009 4017 4025 4033 4041 4049 4057 4065 x (mm) s (m) x (mm)

Diluter + septa Circulating beam Coldex location

x (mm) s (m) x (mm)

Extracted beam Circulating beam Coldex location

Crab Cavity

SPS LSS4: LHC Extraction bump (Q20 optics)

Circulating beam is offset significantly wrt to nominal beam axis

Position cavity axis wrt beam closed orbit position essential => active alignment + beam steering

Acceptable transverse

  • ffset of beam wrt cavity
  • f O(1mm)
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SLIDE 25

Positioning and Alignment

  • Reproducible positioning of cryomodule wrt nominal beam line
  • Actual closed orbit position of beam can be measured (with bypass in)
  • Then cryomodule into beam position with calculated closed orbit offset
  • Cryomodule position tolerance = fraction of cavity alignment tolerance
  • Specifications assumed ~15% of transverse alignment tolerance

=> support table transverse alignment tolerance for =100um

  • Assumes rigid + accurate fixation of cryomodule to support table

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Alignment requires active remote positioning of cryomodule/support table wrt beam closed orbit beam

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SLIDE 26

Positioning and Alignment

  • Reproducible positioning of cryomodule wrt nominal beam line
  • Actual closed orbit position of beam can be measured (with bypass in)
  • Then cryomodule into beam position with calculated closed orbit offset
  • Cryomodule position tolerance = fraction of cavity alignment tolerance
  • Specifications assumed ~15% of transverse alignment tolerance

=> support table transverse alignment tolerance for =100um

  • Assumes rigid + accurate fixation of cryomodule to support table

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Alignment requires active remote positioning of cryomodule/support table wrt beam closed orbit beam Constraints/implications on active alignment within cryostat needs discussion

  • Alignment of cavities within cryomodule
  • Need to understand expected relative mis-alignments due to installation and

thermal cycling - what is expected

  • Offers opportunity to understand how to resolve this for LHC scenario
  • potentially 3 independent cavities per cryomodule
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SLIDE 27

Schedule - Simple Overview of SPS Crab Cavity Run

Cryomodule design/construction SPS CC run 2016 - 2017? Final Design and production

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SLIDE 28
  • Power coupler design completed: Q1 of 2013
  • SM18 - Vertical tests of prototype cavities: start Q2 of 2013
  • Cryostat design ready: End of 2013
  • Cryogenic infrastructure installed in SPS LSS4 : End of SPS LS1
  • Cabling infrastructure in SPS: Q1 of 2014
  • Power Couplers available for cryostat: Q1 of 2015
  • Cryomodule fully dressed: Q2 of 2015
  • SM18 - Cryomodule fully tested: Q3 of 2015
  • Cryomodule installed in SPS in December: 2015-2016 Christmas stop.
  • Crab Cavity validation MDs: SPS Run 2016

Schedule up to Installation in the SPS

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SM18 Cold Test Installation

2013 2014 2015 2016

~ Now

Couplers Ready Cryo Installed Coupler Designed Cryostat Design Crab Cavity Validation Run Cavity Testing

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Version based on Dec 2012 planning

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SLIDE 29

Conclusion

  • An integration envelope for the crab cavities in the SPS now exists
  • Envelope contains cryomodule and its service connections
  • Definition of integration interfaces need to be defined
  • Needs detailed input to define integration + cryostat interfaces
  • Significant integration and space gains can be made if dummy beam

pipe is not at the horizontal on the “SPS-inside” position

  • Active positioning of the cryomodule wrt the beam center is essential
  • Position to be done by control of the support table
  • Active alignment within the cryostat has to be discussed in detail
  • But may help define solution for LHC installation

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