CEPC Cryogenic System Shaopeng Li On behalf of
CEPC Cryogenic System Shaopeng Li On behalf of CEPC cryogenic team Accelerator research center Institute of High Energy Physics(IHEP), CAS CEPC Workshop, Beijing, Nov. 18, 2019
Outline n Introduction n Heat load of cryogenic system for SC cavities n Cooling scheme n Layout of cryogenic system n Cryomodules n Cryogenic system for SC magnets n Summary
Introduction Booster ring: Ø 1. 3 GHz 9 -cell cavities, 96 cavities Ø 12 cryomodules Cryo for IR Ø 3 cryomodules/each station Ø Temperature: 2 K Collider ring: Ø 650 MHz 2 -cell cavities, 240 cavities Ø 40 cryomodules Ø 10 cryomodules/each station Ø Temperature: 2 K IR magnets: Cryo for IR Ø 4 IR magnets, 32 Sextupole magnets, 36 cryomodules Ø 18 cryomodules/each cryo-station Ø Temperature: 4. 5 K
Estimated heat load Higgs Mode Predicted static heat load per cryomodule Cavity dynamic heat load per cryomodule HOM dynamic heat load per cryomodule Input coupler dynamic heat load per cryomodule Module dynamic heat load Connection boxes Cryomodule number Total heat load Total predicted mass flow Unit W Collider 40 -80 K 5 -8 K 300 60 2 K 12 Booster 40 -80 K 5 -8 K 140 20 2 K 3 W 0 0 153. 59 0 0 13. 98 W 20 12 2 2 1 1 W 60 40 6 40 3 0. 4 W W k. W 80 50 161. 59 10 42 50 7. 34 2. 78 4 10 12 0. 41 15. 38 10 17. 20 52 10 40 4. 88 g/s 82. 42 13. 34 12. 73 16. 07 Overall net cryogenic capacity multiplier 1. 54 4. 5 K equiv. heat load with multiplier k. W 1. 99 6. 80 36. 18 0. 32 0. 57 1. 68 Total 4. 5 K equiv. heat load with multiplier k. W 152. 26 346. 58 44. 96 0. 34 2. 57 • Four individual refrigerators will be employed for the CEPC cavity cryogenic system.
Cooling scheme for SC RF cavities • One Cryo-station will supply the cooling for 10 collider cryomodules and 3 booster cryomodules. • The cryomodules have two thermal shields, a 40 K~80 K shield and a 5 K~8 K shield. • A 2. 2 K@1. 2 bar subcooled helium will be supplied for the cryomodules and the 2 K helium gas return to the cold compressors in the cold box.
Process calculation for SC Cavities T: 2. 2 K P: 1. 2 bar m: 91. 95 g/s m: 4. 233 g/s 350 m DN 50 (Φ 60× 1. 6) Q: 10 W a m: 87. 72 g/s c b 1. 196 ba r 8. 656 g/s Q: 9. 7 W 1. 196 ba r 8. 669 g/s d 1. 196 ba r 8. 685 g/s f e 1. 195 ba r 8. 704 g/s 1. 195 bar 8. 725 g/s g 1. 195 ba r 8. 751 g/s Q: 9. 7 W Q: 173. 59 W 80 m DN 15(Φ 22× 1. 6) Q: 173. 59 W j i 1. 195 ba r 8. 826 g/s 1. 195 bar 8. 892 g/s Q: 9. 7 W 350 m DN 300(Φ 325× 4. 0) T: 2. 145 K P: 30. 84 mbar h 1. 195 ba r 8. 783 g/s Q: 173. 59 W k 1. 195 ba r 9. 024 g/s Q: 9. 7 W Q: 173. 59 W m l 1. 199 ba r 1. 349 g/s 1. 199 bar 1. 394 g/s Q: 9. 7 W Q: 18. 38 W 80 m DN 100(Φ 114× 2. 0) 1. 199 ba r 1. 490 g/s
Refrigerator Precooled by Turbine expanders and 31 mbar 2 K gas helium return
The main specification of Refrigerator Designed by TIPC Operating temperature Required capacities Design capacities Pressure(bar)Heat load(W)Equiv. heat load(@4. 5 K) 4. 5 K ---- 1. 25 500 2. 0 K 0. 03 3950 0. 03 4895 12191 40~80 K 18. 5 10300 18. 5 10587 672 5~8 K 5 2720 5 3000 1877 Total equiv. heat load at 4. 5 K 15240 Other parameters Precooled by Turbin expanders Precooled by liquid nitrogen The consumption of the Liquid Nitrogen 0 g/s (0 L/h) 428. 7 g/s(2043 L/h) Gas flow for precooling 100 g/s Gas flow(g/s) 1668 g/s 1551 g/s Power Consumption(KW) 3935. 13 3721. 3 Factor of merit: 258 W/W* 245 W/W*
The parameters of the main compressors Designed by TIPC Parameters Gas flow (g/s)* The high pressure The medium pressure compressor The low pressure compressor 1668. 00 862. 80 230. 7 Pressure of the inlet (bara) 4. 05 1. 05 0. 40 Pressure of the outlet (bara) 18. 54 4. 05 1. 05 85 85 85 2568 1155 196. 3 Adiabatic efficiency ( %) Power consumption (k. W)
The parameters of the cold compressors Designed by TIPC 2 K refrigeration units Parameters The first stage The second stage The third stage Gas flow (g/s) 230. 7 Temperature of the inlet (K) 3. 387 6. 073* 10. 53* Pressure of the inlet (k. Pa) 3. 00 8. 00* 20. 00* Temperature of the outlet (K) 6. 073* 10. 53* 17. 01* Pressure of the outlet (k. Pa) 8. 00* 20. 00* 44. 0 Adiabatic efficiency (%) 60. 0 Power consumption (W) 3208 5323 7765
Infrastructure Each cryo-station has an underground plant in the gallery, the size is 37 m * 8 m.
Layout of CEPC cryogenic system Warm equipment on the ground: compressor hall, helium gas tanks Gallery tunnel Beam tunnel Shaft Refrigerator Cryogenic transfer line 2 K valve boxes Cold equipment under the ground Cryomodule s
Layout of CEPC cryogenic system 2 K Valve box 1. 3 GHz cavity cryomodule Booster part Refrigerator main valve box 2 K Valve box Collider part 650 MHz cavity cryomodule
Cryomodule for 650 MHz 2 -cell cavities • Including six 2 -cell 650 MHz superconducting cavities, six high power couplers, six mechanical tuners and two HOM absorbers Heat Loads Six 2 -cell Cavities Cryomodule 2 K(W) 5 K(W) 80 K(W) POST suport 0. 17 2. 3 20. 67 Overall length(flange to flange, m) 8. 0 Input coupler 0. 46 3. 88 14. 7 Diameter of Vacuum vessel , m 1. 3 Current leads 0. 15 9. 22 27. 89 Beamline height from floor, m 1. 5 Radiation heat 0. 13 0. 86 44. 34 Cryo-system working temperature, K 2 HOM absorber 0 1. 5 4. 5 Number of 200 -POST 6 Other 0 0. 3 1 Total 0. 91 16. 26 107. 6
Test Cryomodule for 650 MHz 2 -cell cavities Ø A test cryomodule with two 2 -cell 650 MHz superconducting cavities will be operated in the PAPS system in 2020.
Test Platform construction n A R&D and test platform of the SC cavity (PAPS) is being constructed from 2017 in Huairou district. n The PAPS project is able to produce and test more than 200 SC cavities and 20 EXFEL-like cryomodules every year. n The test platform consists of three vertical test stations, two horizontal test stations and one beam test station. It will be support the performance test of various type of superconducting cavities. n The test platform will be completed next year.
Layout of PAPS SC test stands Heat Exchanger 1 KW@4. 5 k Cold BOX 2. 5 KW@4. 5 k Cold BOX 5000 L DW 3000 L DW Vertical Test Station Main Distribution Valve Box
Design of 2 K J-T heat exchanger gas helium Fluid Liquid helium Gas helium Inlet temperature(K) 4. 45 2 Inlet pressure(Pa) 1. 25 E+05 3100 2. 2 3. 36 Outlet temperature(K) Table 1 The designed working condition Liquid helium Mass flow rate m=2 g/s m=5 g/s m=10 g/s Axial length of coil finned tube (m) 0. 52 0. 603 0. 691 Axial length of heat exchanger (m) 0. 72 0. 803 0. 891 Pressure drop for the shell side (Pa) 6. 1 30. 6 70. 2 Pressure drop for the tube side (Pa) 36. 2 242 388. 9 Heat exchanger efficiency 91. 8% The design results of J-T heat exchanger for m=2 g/s,m=5 g/s and m=10 g/s Liquid helium gas helium Fig. 1 J-T heat exchanger
Test Platform of 2 K JT heat exchanger Test Cryostat T 2 K Heat load(W) 1. 53 80 K 19. 55
Test result of 2 K JT heat exchanger • The efficiency of the heat exchanger is 85. 3% at the design flow of 5 g/ s and the pressure drop on the return side is 78. 89 Pa. 78. 89 Pa (DP 6314)
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 3 k. W@4. 5 K will be employed for each cryo-stations. Refrigeration: 3 k. W@4. 5 K
Estimated heat loads for SC magnets Name Unit No. IR SC sextupole magnet Valve Box of IR SC sextupole magnet Current lead of IR SC sextupole magnet IR SC magnet Valve Box of IR SC magnet Current lead of IR SC magnet Main distribution valve box Cryogenic transfer-line Total equiv. heat load @4. 5 K with multiplier 1. 5 Cooling capacity of refrigerator@4. 5 K W 32 Heat load for each 10 W 32 20 640 g/s 32 0. 1 3. 2 W W g/s W W W 4 4 4 2 4000 / 30 30 0. 5 50 0. 5 / 120 2 100 2000 3820 W / / 5730 W 2 3000 6000 MW / / 1. 8 Installed power (COP 300 W/1 W) Heat load 320
Cooling scheme for SC IR Magnets • One Cryo-station will supply the cooling for 16 sextupole magnets and 2 IR magnets. • The cryomodule has one 40 K~80 K helium thermal shielding. • A subcooled liquid helium will be supplied for the magnets, then through a JT valve. At that time, the two-phase liquid helium is generated and returned to Dewar.
Summary n Completed the conceptual design of CEPC cryogenic system and determined the cooling scheme n Completed the preliminary design of CEPC refrigerator and the first heat-exchanger will be precooled by Turbin expanders. n A R&D and test platform is under construction, which will support the performance test and mass production of the CEPC superconducting cavity n A detailed design of the CEPC cryogenic system is under way.
Thanks for your attention!
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