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Acceleration & Innovation Workshop: SRF technology

Acceleration & Innovation Workshop: SRF technology. Chris Compton SRF Engineer 10-8-10. Outline. SRF Technology for FRIB SRF Linac SRF Cryomodules SRF Cavities Some FRIB numbers SRF Technical Development Cavity Frequency Control Magnet Systems Thermal Systems Diagnostics

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Acceleration & Innovation Workshop: SRF technology

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  1. Acceleration & Innovation Workshop:SRF technology Chris Compton SRF Engineer 10-8-10

  2. Outline • SRF Technology for FRIB • SRF Linac • SRF Cryomodules • SRF Cavities • Some FRIB numbers • SRF Technical Development • Cavity Frequency Control • Magnet Systems • Thermal Systems • Diagnostics • SRF Infrastructure • Cleanrooms (Class 10,000 and Class 100) • Ultra-pure water • Chemical etching Facility • Cryogenic testing (Dewars and Cryogens) • Electronic test equipment (network analyzer and Signal generator) • Modeling software C. Compton, 8 Oct. 2010

  3. FRIB SRF Linac C. Compton, 8 Oct. 2010

  4. SRF Cryomodules • Cryomodule subassemblies fabricated in industry Magnetic Shield C. Compton, 8 Oct. 2010

  5. FRIB Cavities • FRIB Cavities will be fabricated in industry • Fabricated from high purity niobium HWR, Beta=0.53 subassemblies QWR, Beta=0.0.085 subassemblies C. Compton, 8 Oct. 2010

  6. FRIB numbers • 52 cryomodules required for FRIB driver linac • 4 main cryomodule types • 3 matching cryomodules • 344 cavities required • 4 cavity types • 79 solenoids • QWR, 80.5 MHz, beta=0.041 • QWR, 80.5 MHz, beta=0.085 • HWR, 322 MHz, beta=0.29 • HWR, 322 MHz, beta=0.53 = Cavity QWR 80.5 MHz Beta=0.041 QWR 80.5 MHz Beta=0.085 HWR 322 MHz Beta=0.53 HWR 322 MHz Beta=0.29 = Solenoid C. Compton, 8 Oct. 2010

  7. Cavity Frequency Control • The cavity is driven by an RF amplifier at the accelerator’s RF frequency of 80.5 MHz or 322 MHz • Mechanical movements can shift the cavity’s frequency, requiring additional external power to maintain operational parameters • Mechanical movement is caused by surrounding conditions • Mechanical vibrations (i.e. pumps, compressors) • Pressure fluctuations from the cryogenic plant • Mechanical movement must be mitigated or compensated C. Compton, 8 Oct. 2010

  8. Cavity Frequency Control • Cavity Tuner – used to mechanically tune cavity to desired frequency • Design challenges • Minimize backlash in tuner • Precision stepper motor control • Piezo actuators • Feed-back system • Mechanical isolation • Damper systems to isolate noise sources (i.e. pumps, compressors) • Isolate cryomodules C. Compton, 8 Oct. 2010

  9. Magnetic Systems • Magnetic Shielding • Cavity performance is sensitive to magnetic fields • Cavity must be shielded from both solenoid and earth fields • Magnet leads • Current design uses vapor cooled leads (4.5K operation) • Redesigning lead cooling method to meet FRIB cryogenic plant parameters • Alternative: redesign with HTC leads (possible 2K operation) • Magnetic Degaussing • Degauss cycle to remove possible trapped flux C. Compton, 8 Oct. 2010

  10. Thermal Systems • Thermal shield development • Current design uses a copper thermal shield • Redesign under investigation to use aluminum for production • Static load mitigation • Thermal intercept design • Cryogenic flow and cooldown • Cryomodules to be cooled quickly (operational schedule) • Cavity to be cooled quickly (cavity performance) • Plan to pre-cool parts (solenoids, etc) with cavities still warm C. Compton, 8 Oct. 2010

  11. Diagnostics • Temperature sensors at cryogenic conditions • Mounting techniques not yet perfected • Magnetic Probes • Wide range desired • Electrical feed-throughs under cryogenic conditions • Feed-through with direct contact with cryogenics (superfluid) • X-ray monitoring and imaging • Used to diagnose performance • Have investigated techniques to localize field emitters with x-rays C. Compton, 8 Oct. 2010

  12. SRF Infrastructure • Cleanrooms (Class 10,000 and Class 100) • 1,000 sq.ft. • Ultra-sonic cleaners plumbed with ultra-pure water • Ultra-pure Water • Supplied at ~ 18 MΩ-cm • Chemical Etching Facility • Cryogenic Testing (Dewars and Cryogens) • Liquid helium (4.2K) supplied by cryoplant • Sub-atmospheric system allows testing to ~1.5K • Cleanroom to Dewar transfer ability • RF Testing (phase feedback loop, amplifier, etc) • Modeling Software • Mechanical structure – Ansys, Solidworks • Electro-magnetic – Analyst • Dynamic – CFX, Fluent C. Compton, 8 Oct. 2010

  13. Contacts • For further information please contact: • Matthaeus Leitner – Chief Engineer - lienter@frib.msu.edu • Walter Hartung – SRF Physicist - hartung@frib.msu.edu • Chris Compton – SRF Engineer – compton@frib.msu.edu C. Compton, 8 Oct. 2010

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