Linac Cryostat Design Priorities

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Linac Cryostat Design Priorities

• Ken Shepard
• ANL Physics Division
• for Proton Driver Discussion/Planning
• May 3, 2005 at FNAL

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ATLAS PII Cryomodule common cryogenic cavity
vacuum
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High-pressure water rinsing gives a dramatic
improvement in super-conducting cavity
performance.
Argonne, Spring 2001
Q
Los Alamos, Spring 2001
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Linac Cryostat Design Priorities / Strategies

• Enable clean assembly of cavity string
• Maintain clean condition of cavity string
• Separate cryogenic and cavity vacuum systems
• Provide for simple and clean integration into
  linac
• Enable and maintain cavity alignment
• Maximize reliability
• Minimize costs
• Minimize clean room work
• Cryogenic performance
• Integrate design with linac tunnel

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Performance Projection Experience BaseSNS
Production
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RIA Cryomodule Assembly
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Couplers Tuners for the RIA Cryostat
10 kW variable coupler from room ambient to 4 K
Pneumatic slow-tuner yoke for QWR and coaxial HW
cavities
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RIA Cryomodule Assembly
Clean-room assembly to this point
Cavities are sealed up in a clean environment
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RIA Cryomodule Assembly
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RIA Cryomodule Assembly
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Test Cryostat Design Priorities Strategies

• Enable tests of a variety of types of cavities,
  couplers, and frequencies.
• Test procedure and environment should be
  compatible with best-case, most stringent linac
  operating procedures and environment
  (Low-particulate procedures require separate
  cavity and cryogenic vacuum systems)
• The test cryostat system should be as flexible as
  possible
• The test cryostat should provide rapid
  turn-around
• The test cryostat should facilitate a variety of
  diagnostic techniques
• Provide for well-controlled operation over the
  temperature range 1.8 4.5 K.
• Permit cryogenic load measurements with 0.1 watt
  or better resolution
• Magnetic shielding to less than 10 mG at niobium
  cavity surfaces
• Tolerate heat loads of as much as several hundred
  watts over appreciable time periods (minutes to
  hours).

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RIA Cavities being developed at ANL
170 MHz, ? 0.26, coaxial ½ wave cavity
(complete tested)
115 MHz, ? 0.15, steering- corrected cavity
(complete)
345 MHz, ? 0.4, double-spoke cavity (built
tested)
345 MHz, ? 0.5 and 0.62, triple-spoke cavities
(complete in July 2004))
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Design concept for general-purpose test cryostat
Needed to enable true clean-assembly, improve
turnaround, and enable 2 k testing