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CEPC Cryogenic System

Detailed overview of the design and operation of a sophisticated cryogenic system for superconducting cavities in particle accelerators, including cooling schemes and infrastructure layout.

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CEPC Cryogenic System

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  1. CEPC Cryogenic System Shaopeng Li, Jianqin Zhang,Ruixion Han Accelerator research center Institute of High Energy Physics(IHEP), CAS CEPC Workshop, Oxford,UK, April 15, 2019

  2. Outline • Introduction • Heat load of cryogenic system for SC cavities • Cooling scheme • Layout of cryogenic system • Cryomodules • Cryogenic system for SC magnets • Summary

  3. Introduction Booster ring: • 1.3 GHz 9-cell cavities, 96 cavities • 12 cryomodules • 3 cryomodules/each station • Temperature: 2K Collider ring: • 650MHz 2-cell cavities, 240 cavities • 40 cryomodules • 10 cryomodules/each station • Temperature: 2K IR magnets: • 4 IR magnets, 32 Sextupole magnets, 36 cryomodules • 18 cryomodules/each station • Temperature: 4.5K Cryo for IR Cryo for IR

  4. Parameters of SC cavities related for Cryogenic system

  5. Estimated heat load • Four individual 18kW@4.5K refrigerators will be employed for the CEPC cavity cryogenic system.

  6. Flowchart of one Cryo-station • Each Cryo-station mainly includes Compressor, Cold box, helium gas storage tanks, cryomudules and purification system. • The cryomodules have two thermal shields, a 40K~80K shield and a 5K~8K shield. • A 2.2K@1.2bar helium will be supplied for the cryomodules and the 2K helium gas return to the cold box with the cold compressors.

  7. Refrigeration and 31mbar 2K gas helium

  8. Cooling scheme for Collider

  9. Cooling scheme for Booster

  10. Infrastructure Each cryo-station has an underground plant in the gallery, the size is 37m * 8m.

  11. Layout of CEPC cryogenic system Warm equipment on the ground: compressor hall, helium gas tanks Beam tunnel Gallery tunnel Shaft Refrigerator Cryogenic transfer line Cold equipment under the ground 2K valve boxes cryomodules

  12. Layout of CEPC cryogenic hall High pressure helium cylinders Piston compressors 10*100m3 helium gas Pressure vessels Helium gas bag Helium purifier Electrical control system Recycle screw compressors 4*50m3 LN2 Storage Tanks

  13. Tunnel Cross section Gallery Tunnel Beam Tunnel Refrigerator Transfer line 1.3GHz cryomodule 650MHz cryomodule 2K valve box

  14. Layout of CEPC cryogenic system 1.3GHz cavity cryomodule 2K Valve box Booster part Refrigerator main valve box 650MHz cavity cryomodule Collider part 2K Valve box

  15. R&D He II peak heat and the riser pipe of cryomodule • He II Peak heat • peak heat is relevant with the length, the diameter and the temperature. • q*L1/m is the function of the working temperature, where m=3 or 3.4. Where Q is the peak heat, q* is the peak heat flux, L is the length of the tube, r is the radius of the tube; m is a constant. m=3 L=12.5cm m=3 • Peak heat increases with the work temperature decreasing, which increases with the diameter of riser pipe increasing. • Peak heat flux decreases with the vertical distance increasing.

  16. R&D He II peak heat and the riser pipe of cryomodule (Reference from Tom Peterson) • 1.3GHz 8*9 cell SC cryomodule for Booster Suppose L=30cm, T=2K, q*L1/3=4.85 W/cm3 • 650MHz 6*2cell SC cryomodule for Collider Suppose L=30cm, T=2K, q*L1/3=4.85 W/cm3 • 1 W/cm2 is a conservative rule for a vertical pipe at 2K. • Since the pipe is non-vertical and 2K is the lower temperature, the diameter for riser pipe is 5.5cm for TTF and 9.5cm for LCLS-II. 1.3GHz cryomodule LCLS-II 9.5cm/110.5W CEPC 5.5cm/37W It is suggested that the riser pipe for CEPC booster cryomodule is 5.5 cm with the peak heat of 37 W. 650MHz cryomodule CEPC 9cm/99.2W It is suggested that the riser pipe for CEPC collider cryomodule is 9 cm with the peak heat of 99.2 W.

  17. Cryomodule for 650MHz 2-cell cavities • Including six 2-cell 650 MHz superconducting cavities, six high power couplers, six mechanical tuners and two HOM absorbers

  18. Test Cryomodule for 650MHz 2-cell cavities • A test cryomodule with two 2-cell 650 MHz superconducting cavities will be operated in the PAPS system in 2020.

  19. CEPC test cryomodule and valve box

  20. Cryomodule for 1.3GHz 9-cell cavities • Design Goals: • Low heat loss • Fast cool down XFEL / LCLS-II type Cryomodule for High Q Cavity • Cryogenic Group in IHEP has manufactured 58 1.3GHz 9-cell Cryomodules for EXFEL cooperated with local companies. • It’s a good foundation for the optimization design for the CEPC cryomodules.

  21. Cryogenics for SC magnets • Two interaction region in CEPC ring, each IR has 2 IR magnets and 16 sextupole magnets. • A refrigerator with the cooling capacity of 3kW@4.5K will be employed for each cryo-stations. Refrigeration: 3kW@4.5K

  22. Estimated heat loads for SC magnets

  23. Summary • Completed the conceptual design of CEPC cryogenic system and determined the cooling scheme • The required cooling capacity of the superconducting cavity cryogenic system and the superconducting magnet cryogenic system is 72KW@4.5K and 6KW@4.5K respectively. • A detailed design of the cryogenic system is under way.

  24. Thanks for your attention!

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