History of the TESLA Cryomodule Design

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History of the TESLA Cryomodule Design Operation

• J. G. Weisend II
• SLAC
• July 2004

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Outline

• Evolution of cryomodule design
• Why were certain choices made
• What worked
• What was changed
• The results presented are a results of the hard
  work of many at DESY, INFN, FNAL and other labs.
• The authors efforts were carried out while he
  was at DESY.

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1st Generation TESLA Cryomodule

• Fundamental design aspects
• 3 composite posts (1 fixed, 2 sliding) provide
  support and alignment adjustment
• 300 mm pipe is the structural backbone
• It is also sized for pressure drop in TESLA 500
• Flexible couplers (cavities move with 300 mm
  pipe)
• Radiation shields held together by fasteners. Cu
  straps to cooling pipes

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1st Generation TESLA Cryomodule

• Fundamental design aspects
• Legacy eccentric disks
• Larger OD and less intuitive adjustment
• Low cost a consideration from the start
• Long structure
• Welded connections
• Large amounts of RD instrumentation

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Side View of 1st Generation TESLA
Cryomodule(each end of 300 mm tube shrinks 15
mm upon cooldown)
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Cross Section of 1st Generation TESLA Cryomodule
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Some TESLA Requirements
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2nd Generation Cryomodule

• Same basic cross section
• Welded thermal radiation shields no Cu straps
  to cooling lines
• Simplified tolerances
• Less RD instrumentation
• Cold mass significantly less expensive to produce

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Alignment ResultsCryomodule 1
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Alignment ResultsCryomodule 2
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Static Heat LeakMeasurements
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3rd Generation Cryomodule

• Allows for fixed couplers
• Invar rod and roller bearings allow cavities to
  remain fixed while the 300 mm tube shrinks
• Eccentric disks are gone
• More intuitive alignment results
• Smaller cross section results in standard pipe
  size for outer vessel
• Axial position of last support changed to stiffen
  structure near quadrupole

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Changes for future Cryomodules

• XFEL
• Quadrupole now cooled to 2 K
• Quadrupole uses HTSC leads
• TESLA 500
• Quadrupole also moved to center of cryomodule
• 12 cavities per module
• Final design not finished

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Comments

• The cryomodule design is well developed and
  tested. The design requirements could be met.
• The addition of the fixed coupler option was a
  significant improvement
• Further simplification of the coupler design (if
  possible) would be beneficial
• Assembly of the cryomodule is straightforward but
  using this design does require large assembly and
  alignment fixtures
• The need for the 4.5 K shield was investigated
  for the TESLA 500 machine. It was kept. Its
  utility for smaller machines should be
  reexamined.