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Some considerations on Cryogenic system for 9-cell SC cavities test at IHEP

Some considerations on Cryogenic system for 9-cell SC cavities test at IHEP. Accelerator research center Shaopeng Li The Third IHEP-KEK 1.3GHz SC Technology Collaboration Meeting Dec. 7-8, 2010, IHEP, Beijing. contents ：. Horizontal test stand of BEPCII 500MHz SC cavities

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Some considerations on Cryogenic system for 9-cell SC cavities test at IHEP

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  1. Some considerations on Cryogenic system for 9-cell SC cavities test at IHEP Accelerator research center Shaopeng Li The Third IHEP-KEK 1.3GHz SC Technology Collaboration Meeting Dec. 7-8, 2010, IHEP, Beijing

  2. contents： • Horizontal test stand of BEPCII 500MHz SC cavities • Some considerations on cryogenic system for 2K 9-cell cavities test at IHEP

  3. Layout of BEPCII cryogenic system

  4. Cryogenic hall and tank farm • Facilities • He compressor systems, VFDs, air compressor, air drier, ORS, cooling-water system, spare power engine, gas tank farm, control system • Tank farm Two 130m3 ,1.45Mpa Two 130m3 ,0.73Mpa One 30m3 ,0.08Mpa One 5m3 ,6Mpa One 10m3 ,0.73Mpa

  5. BEPCII second colliding hall heater Waveguide SRF quench line LN2 transfer line UPS SRF Cavity (On line) PLC rack 500W refrigerator LHe dewar Multi-channel transfer line SRF valve box SRF Cavity test stand

  6. Horizontal test stand for BEPCII 500MHz SC cavities Horizontal test stand 500MHz SC cavity Operation position

  7. Some considerations on 9-cell SC cavities test • The feature of vertical test of 9-cell SC cavity • Short term test, low power test • Open cycle and Close cycle system • Open cycle :normal test cryostat, but recovery and purify system； • Close cycle: special test cryostat with tight leakage • Depressurized pumping system； • Off-line or on-line liquifier/refrigerator • The feature of horizontal test of 9-cell SC cavity • Continuous and long term running • Close cycle system, high power test • Depressurized pumping system； • On-line liquifier/refrigerator

  8. Pure storage tank Pure storage tank Impure storage tank 80K purifier Helium liquified plant Storage dewar Liquifier pump Gas bag Recovery compressor LHe mobile Dewar Vertical test stand Pure storage tank pump Liquifier/refrigerator Vertical test stand Flow diagram of Vertical test Open cycle Close cycle

  9. 2000L Dewar Flow diagram of vertical/horizontal test Recovery&purity system Pumping unit Heater Heat exchange Vertical test stand 4K Valve Box 2K Valve Box 500W 4.5K refrigerator Main Comp. Horizontal test stand

  10. Normal methods to 2K • Case 1：Directly to depressurize saturated vapor pressure of helium • Case 2：Depressurization + JT； • Case 3：Depressurization +JT + Hex；

  11. Directly to depressurize the saturated vapor pressure of LHe in test cryostat by pumping system and then the low temperature can be produced Pumping system 1.8K， 16mbar Total heat loss Q=100W Case 1：Directly to depressurize • During the SC cavities test, the LHe of test cryostat will be consumed and LHe level will be lowered ； • The heat loss of 1W@1.8K will consume 1.08L/h • To assume total heat load 100W，the mass flow rate will be LHe 4.37g/s and LHe consumption is 108L/h Vertical test cryostat

  12. The LHe throttled directly to test dewar from storage dewar； Isoenthalpy thrrotle h1=h2 =h2Gx+h2L(1-x)，h1 is enthalpy value at 4.2K；h2G and h2L are enthalpy at 1.8K LHe and GHe；x is helium fluid quality ； Energy equation：mh2+Q=mh4，h4 is enthalpy at 1.8K GHe，m is mass flow rate The produce of liquid helium is about 61% from 4.2K to 1.8K If total heat loss is 100W，the total mass flow rate of helium is around 7g/s pump 2000L Dewar Saturated LHe 4.2K，1.0bar 1 JT 4 2 1.8K， 16mbar Vertical test dewar 3 Toatl heat loss Q=100W Case 2：Depressurization + JT T-S diagram

  13. Case 3：Depressurization +JT+ heatexchange 2000L dewar Pump • The flow pass through the heatexchange to be cooled by return cold GHe and then it will be throttled to more low temperature by JT； Saturated LHe 4.2K，1.0bar 2 1 5 JT 4 6 1.8K， 16mbar Vertical Test dewar 3 Total heat loss Q=100W

  14. Comparison of three methods • Case 1：No JT and HEX, Ease operation and simple. But it has to be interrupted when the LHe level lower to the value of limitation and then refilling LHe again. • Case 2：No heatexchange，lower efficiency. But it can maintain and extend the test time • Case 3：Complex ，higher efficiency. It’s normal to be used in cryogenic system of accelerator.

  15. Calculation of pump speed

  16. Performance curve of Edwards EH1200 Roots pump 1000m3/h 1mbar is the limitation of vacuum of Mechanical pump

  17. Equivalent heat load at 1.5K for 1.8K design

  18. Heat power to room temperature for return pipe

  19. Recovery and purify system

  20. Summary • The pump speed will be choosed according to the heat loss of 20W at 1.8K, that is around the capacity of 1000m3/h • The capacity of recovery and purify system are to be thought with the heat loss of 100W at 1.8K and the capacity will be 100m3/h or 4.5g/s • The design and calculation in detail for 2K test system are still underway

  21. Tanks for your attention！

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