Project X Cryomodules

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Project X Cryomodules

• Tom Peterson and Yuriy Orlov
• with material from our SRF cavity and cryomodule
  design team
• 21 February 2011

650 MHz Cryomodule Design, 21 Feb 2011
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Project X Reference Design
Cryomodules for CW linac
650 MHz Cryomodule Design, 21 Feb 2011
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SRF LinacTechnology Map
Pulsed
CW
Section Freq Energy (MeV) Cav/mag/CM Type
SSR0 (?G0.11) 325 2.5-10 18 /18/1 SSR, solenoid
SSR1 (?G0.22) 325 10-42 20/20/ 2 SSR, solenoid
SSR2 (?G0.4) 325 42-160 40/20/4 SSR, solenoid
LB 650 (?G0.61) 650 160-460 36 /24/6 5-cell elliptical, doublet
HB 650 (?G0.9) 650 460-3000 160/40/20 5-cell elliptical, doublet
ILC 1.3 (?G1.0) 1300 3000-8000 224 /28 /28 9-cell elliptical, quad
InPAC 2011 J. Kerby
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Design team

• 650 MHz cryomodules
• Camille Ginsburg, Yuriy Orlov, and Prashant Khare
  are leading and organizing the effort with me
• Cavities, input couplers, magnets, magnet current
  leads, tuners, instrumentation, 325 MHz
  cryomodules, microphonics, etc.
• Many other people within Fermilab and within the
  Project X collaboration

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Approach

• CW cryomodules with as much as 25 W per cavity at
  2 K and tight constraints on cavity frequency
  present some different problems from TESLA/ILC
  cryomodules
• Over 200 W at 2 K per cryomodule as opposed to
  about 12 W at 2 K per cryomodule
• Lets look at the requirements, consider what
  other labs have already done, and select best
  features for our own design

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Our plan

• Analyses, modeling, and reviews of various
  concepts based on existing designs
• Following visits to HZB, DESY, and TTC meeting
  (Feb 21 - Mar 3), down-select a more specific
  design approach
• Goal is to have a specific 650 MHz cryomodule
  design proposal for discussion before the Project
  X Collaboration meeting (April 11)
• Also complete (draft) specifications and
  fundamental CM parameter lists in this timeframe

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General arrangements under consideration

• Segmentation level and cavity support structure
• String BESSY/HZB (and Cornell ERL) liquid
  managed separately for each CM, 2-phase pipe
  closed at each end, but otherwise a string, TESLA
  style piping and supports
• Stand-alone three options for configuration at
  the individual cryomodule level
• Completely close a TESLA style CM at each end
• Eliminate 300 mm pipe -- space frame support
• Eliminate 300 mm pipe -- support posts and frame
  (325 MHz concept from Tom Nicol)
• Helium vessel
• Closed, TESLA-style, 2-phase pipe connected to
  helium vessel
• Open, Jlab/SNS style, 2-phase flow through helium
  vessel

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Cryomodule style

• Very high heat flux (200 W per CM) and relatively
  short linac (not large quantity production nor
  several km long strings) gt
• Need separated liquid management
• Prefer small heat exchangers, distributed with
  cryomodules
• Prefer stand-alone cryomodules, warm magnets and
  instrumentation between cryomodules like at SNS
• Stand-alone CM gt
• 300 mm pipe is unnecessary for helium flow
• Not need 300 mm pipe for helium flow gt
• Empty 300 mm pipe as support backbone or
• Different support structure (space frame or
  posts)

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Helium vessel style

• Helium vessel style (open vs. closed) is
  independent of support style (hung from 300 mm
  pipe or not)
• High heat loads and tight pressure stability gt
• Large liquid-vapor surface area for liquid-vapor
  equilibrium
• Acts as thermal/pressure buffer with heat and
  pressure changes
• Linac is short enough that total helium inventory
  not an issue gt
• Open helium vessel is feasible
• For the stand-alone CW cryomodule, a closed
  TESLA-type helium vessel may be favored by
• Tuner design
• Input coupler design
• And allowed by reduced pressure sensitivity

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SNS vs TTF cryomodule
TTF vacuum vessel string. End boxes and
bellows would become part of vacuum/pressure
closure
SNS (like CEBAF) self-contained vacuum vessel
stand-alone style
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Cryomodule requirements -- major components

• Eight (8) dressed RF cavities
• Eight RF power input couplers
• One intermediate temperature thermal shield
• Cryogenic valves
• 2.0 K liquid level control valve
• Cool-down/warm-up valve
• 5 K thermal intercept flow control valve
• Pipe and cavity support structure
• Instrumentation -- RF, pressure, temperature,
  etc.
• Heat exchanger for 4.5 K to 2.2 K precooling of
  the liquid supply flow
• Bayonet connections for helium supply and return

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Cryomodule requirements -- major interfaces

• Bayonet connections for helium supply and return
• Vacuum vessel support structure
• Beam tube connections at the cryomodule ends
• RF waveguide to input couplers
• Instrumentation connectors on the vacuum shell
• Alignment fiducials on the vacuum shell with
  reference to cavity positions.

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Cryomodule requirements -- slot length
650 MHz cavities at 2 K
11.3 meters
Warm magnets and instrumentation
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Cryomodule requirements -- thermal

• Cavities at nominally 2 K
• 1.8 K to 2.1 K, to be determined
• One radiative thermal shield at nominally 70 K
• 35 K to 80 K to be determined
• Thermal intercepts at nominally 5 K and 70 K

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Cryomodule requirements -- vessel and piping
pressures
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Design considerations

• Cooling arrangement for integration into cryo
  system
• Pipe sizes for steady-state and emergency venting
  
• Pressure stability factors
• Liquid volume, vapor volume, liquid-vapor surface
  area as buffers for pressure change
• Evaporation or condensation rates with pressure
  change
• Updated heat load estimates
• Options for handling 4.5 K (or perhaps 5 K - 8 K)
  thermal intercept flow
• Alignment and support stability
• Thermal contraction and fixed points with closed
  ends
• Etc.

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Cryomodule Pipe Sizing Criteria

• Heat transport from cavity to 2-phase pipe
• 1 Watt/sq.cm. is a conservative rule for a
  vertical pipe (less heat flux with horizontal
  lengths)
• Two phase pipe size
• 5 meters/sec vapor speed limit over liquid
• Not smaller than nozzle from helium vessel
• Gas return pipe (also serves as the support pipe
  in TESLA-style CM)
• Pressure drop lt 10 of total pressure in normal
  operation
• Support structure considerations
• Loss of vacuum venting P lt cold MAWP at cavity
• Path includes nozzle from helium vessel, 2-phase
  pipe, may include gas return pipe, and any
  external vent lines

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Concept -- TESLA style with open pipe as support

• Use an open 300 mm dia pipe as the support
  structure backbone
• Open to insulating vacuum
• Direct connection from 2-phase pipe to vapor
  return line via heat exchanger
• Direct connection from 2-phase pipe to vent line
• 2-phase pipe sized large for venting from one end
  
• Advantages
• 300 mm pipe open for handling with present
  tooling
• No end forces on 300 mm pipe or connections to it

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Stand-alone cryomodule schematic
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650 MHz Cryomodule (Tesla Style-Stand Alone)
Vacuum vessel Cold mass supports (21)
Power MC (8)
Beam
End Plate
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650 MHz layout
Fix. support
Sld. support
Sld. support
300mm pipe (backbone) 650 MHz cavity
Gate valve End plate
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X-Y section
-48 vacuum vessel 300 mm pipe -80K shield,
pipes (Nom 35mm-ID) -Warm up-cool down pipe
(nom 25mm ID) -4K return pipe (nom 25mm
ID) -650 MC -Thermal intercept to MC 80k 4K
-2-Phase pipe (161mm-ID) -80K Forward pipe -4K
Forward pipe (?) -Thermal intercept 2-phase pipe
to 300mm pipe (?)
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650 MHz cryomodule. End plate not shown.
Heat exchanger (Location on the middle of
CM650??) 300mm pipe
Access to bayonet connections
Cryo-feed snout with cryogenic connections (Locati
on on the middle of CM650??)
Access to HX and U-turn connections
Gate Valve
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Cavity string 300mm pipe upstream side
Heat exchanger Vent line with check
valve 2-phase pipe connection to HX
Two He reservoirs with level sensor
Cavity needle supports VAT needle supports (?)
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Cavity string 300mm pipe downstream side
2-phase pipe Thermal compensator Blank Flange
support
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Dressed cavity 650 MHz. (proposal) with MC
cold-part
Ti Helium vessel OD- 450.0 mm Ti 2-Phase pipe
ID- 161.5 mm Ti 2-Phase chimney ID- 95.5 mm
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Other concepts

• Single Spoke Resonator cryostat concept using
  support posts under the cavities and magnets
• We may adapt that design to a 650 MHz CM
• SNS/Jlab 12 GeV upgrade style space frame
  supports
• Well-developed design, works well
• BESSY/HZB CW cryomodule string rather than
  stand-alone cryomodules
• Eliminate external transfer line (?)
• Cornells ERL cryomodule has some interesting
  features to consider although somewhat different
  issues

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Conclusions

• Many very good ideas and much work have already
  gone into cryomodule design
• Systems are different with differing requirements
  
• Generally means adapting but not copying design
  concepts
• We greatly appreciate the exchange of ideas and
  information which have been and will continue to
  be an important part of our work

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Backup slides
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Cryo Schematic -- flow through 300 mm pipe
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Empty pipe for support only or no 300 mm pipe
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SSR1 CM concept
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650 MHz Cryomodule layout (follwing SSR concept)
Heat Exchanger pipe 2- phase He pipe (Ti)
Vacuum vessel Cold mass 650 MHz Cavity 2 Support
posts for each cavity Z-fix Z-free? Cavity MC
port -stabile
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650 MHz Cryomodule (following SSR concept)
Heat exchanger Vent line with check valve
Control valves Bayonet connection
Beam pipe at the center of CM650
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650 MHz Cryomodule section. (SSR-style concept)
Heat exchanger Cryo feed snout
Vacuum vessel pipe-48OD XFEL style cavity (SNS
style)
80K shielding Cold mass tray Tray supports
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Jlab space frame
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Jlab space frame
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Jlab space frame
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Separate liquid management in each cryomodule but
no external transfer line
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ERL injector cryomodule
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ERL cryomodule features
Figure 1 from CRYOGENIC HEAT LOAD OF THE CORNELL
ERL MAIN LINAC CRYOMODULE, by E. Chojnacki, E.
Smith, R. Ehrlich, V. Veshcherevich and S.
Chapman, Cornell University, Ithaca, NY, U.S.A.
Published in Proceedings of SRF2009, Berlin,
Germany
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ERL cryomodule features

• TESLA-style support structure -- dressed cavities
  hang from gas return pipe (GRP), but
• Titanium GRP
• No invar rod, no rollers
• 6 cavities per CM, 9.8 m total CM length
• HOM absorbers at 40 - 100 K between cavities
• GRP split with bellows at center, 4 support posts
  
• Helium vessels pinned to GRP
• Some flexibility in the input coupler
• De-magnetized carbon-steel shell for magnetic
  shielding (this is like TTF)
• 2-phase pipe closed at each CM end, JT valve on
  each CM (like BESSY design)
• String rolls into vacuum vessel on rails

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RRCAT contributions

• RRCAT (Indore) is collaborating with Fermilab on
  650 MHz cryomodule designs
• Present focus is TESLA-style

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Glimpses of 3-D Model (contd)

SCRF Cavity supported on HGR pipe

• Information required on
• Magnet package
• Tuner details
• Power Coupler

• The model incorporates a modified Cavity support
  system.
• 2K helium supply line includes a bellow in
  vertical configuration

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Glimpses of 3-D Model (contd)
Thermal Shield with dressed Cavity

• 80K- Thermal shield
• 5K-Thermal shield is partial
• (Upper Part only).

• Thermal shield 80K shield .
• Thermal shield 5K shield is partial.

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