Rossana Bonomi R. Bonomi TE-MSC-CMI SPL Seminar 2012

Outline SPL Short cryomodule heat loads and refrigeration powers Thermal analyses of components Double-walled tube Cold-warm transition Vacuum vessel and thermal shield Mock-up 1 R. Bonomi TE-MSC-CMI SPL Seminar 2012

Short Cryomodule 2 R. Bonomi TE-MSC-CMI SPL Seminar cavities, 4+1 DWT, 2 CWT

Heat contributions from: Double-walled tubeto 2 K, 4.5 K Cold-warm transitionto 2 K, K Vacuum vesselto K Thermal shieldto 2 K Cryomodule temperature levels Temperature levels: Bath2 K Inlet helium gas4.5 K Thermal shield50-70 K Vacuum vessel300 K TS VV CM CWT DWT 3 R. Bonomi TE-MSC-CMI SPL Seminar 2012 Very important for thermodynamic costs

Cryomodule heat loads SubassemblyTypeSource Desti- 2 K 4.5 K K [W] Double-walled tube DWT cd rad RF DWTbath 13 (1) x 5 = (2) x 5 = (3) x x 1 = (4) x x 1 = cvDWTgas----- (1) 60 (2) x 5 = (3) x 5 = (4) - Cold-warm transition * CWT cdWFTS x 2 = 46.0 cdTSCM 0.8 x 2 = x 2 = x 2 = x 2 = radWF + wallCM 1.0 x 2 = x 2 = x 2 = x 2 = radWFTS x 2 = 0.4 Vacuum vessel VV rad **VVTS Thermal shield TS rad **TSCM Cavity ***RFcavityCM- (1) - (2) 20.0 (3) x 4 = (4) x 4 = TOT for SCM [W]69.7 (1) 5.2 (2) 86.8 (3) (4) -300 (2) 300 (3) DWT Static heat loads (1) RF off, cool off (2) RF off, cool on DWT Dynamic heat loads (3) RF on, cool on (4) RF on, cool off * Thermal shield at 50 K, placed at 0.15 m from cold flange ** C. Maglioni, V. Parma’s technical note: “Assessment of static heat loads in the LHC arc, from the commissioning of sector 7-8”, LHC Project Note 409, 2008 (VV  TS 1.7 W/m 2 - TS  CM 0.1 W/m 2 ) *** V. Parma’s presentation: 4

@ 2 K (990 W el /W th K (16 W el /W th 4.5 K, non-isothermal: 40 mg/s warm gas are equivalent to 4 W 4.5 K (100 W th /(g/s)) 4 W 4.5 K cost 880 W el (220 W el /W th *) For 4+1 DWT  4.4 kW el (1)70 W th 69.3 kW el (2)5 W th 5.0 kW el (3)87 W th 86.1 kW el (4)194 W th kW el Cryomodule refrigerator powers Static operations Dynamic operations 79 W th 1.3 kW el * S. Claudet et al. “1.8 K Refrigeration Units for the LHC: Performance Assessment of Pre-series Units”, proceedings ICEC20 5 When DWT is actively cooled, power is less than half ! R. Bonomi TE-MSC-CMI SPL Seminar 2012

Around 92 kW el of refrigerator power are expected during nominal operation for the SPL short cryomodule (4 cavities) Heat loads due to instrumentation, HOMs and critical regions have not been considered yet Cryomodule tot refrigerator power 6 R. Bonomi TE-MSC-CMI SPL Seminar 2012

Double-walled tube Semi-analytical model * 1D, 3 layers, 22 nodes Material properties: Cryocomp Gas properties: Hepak L= 300 mm, flange-flange length D= 50 mm, internal diameter S= 1152 mm 2, conductive section m= 40 mg/s, helium mass flow (laminar) * Based on O. Capatina ‘s presentation: 7 R. Bonomi TE-MSC-CMI SPL Seminar 2012 Inner wall: average thermal conductivity Cu-SS

Double-walled tube 8 R. Bonomi TE-MSC-CMI SPL Seminar 2012 Copper layer accounts for 5-7% of tot heat conducted

Double-walled tube Results are comparable with FE 2D simulations (Comsol) Heat load at bath: < 0.5 W RF power: 10.1 W Antenna radiative load (330 K): 0.6 W Thermal contraction: < 1 mm 9 RF power, No COOL 40 mg/s He Heat to He bath reduced to less than 2% R. Bonomi TE-MSC-CMI SPL Seminar 2012

Double-walled tube RF currents node position is critical.. Shift [mm]Prf [W]Qrad (W)Qbath [W] RF currents 10 R. Bonomi TE-MSC-CMI SPL Seminar 2012

(Figure from: « An Introduction to Cryogenics », Ph.Lebrun, CERN/AT ) He refrigerationHe Liquefaction Thermodynamic efficiency of DWT gas cooling How to compare isothermal and non- isothermal processes ? Electrical power for liquefaction of 1 g/s helium: 6200 W el Carnot 4.5 K: 66 W el /W th 1 g/s liquid helium is equivalent to 100 W 4.5 K * 11 * U. Wagner s note: R. Bonomi TE-MSC-CMI SPL Seminar 2012

Thermodynamic efficiency of DWT gas cooling Comparison with other ways of cooling (heat intercepts, self-sustained cooling) 2 K, K, 80 K 2K [W] P [W el ] 9K [W] P [W el ] 80K [W] P [W el ] vapours rate [g/s] Q 4.5K [W] (1g/s=100W) P [W el ] Total power [Wel] A) No intercept , B) 1 optimised 80K 2.22, ,892 C) 2 optimised 80K & 9K ,372 D) 4.5K self-sustained vapour cooling E) He vapour cooling (4.5K-300K) F) He vapour cooling (4.5K-300K), RF power on ,375 G) No He vapour cooling, RF power on 2221, R. Bonomi TE-MSC-CMI SPL Seminar 2012

Cold-warm transition Mathcad/Matlab analytical analysis for each position and temperature of thermal shield Heat due to radiation and to conduction are evaluated through equivalent electric analysis TS 13 R. Bonomi TE-MSC-CMI SPL Seminar 2012

Cold-warm transition Heat to TS [W] Heat to BATH [W] Cold flange Warm flange REAL refr power [kW el ] Cold flange Warm flange 14 R. Bonomi TE-MSC-CMI SPL Seminar 2012 TS optimal position for minimisation of required refrigerator power Each CWT could evaporate helium for 2 DWTs (2 W=>95 mg/s)

Vacuum vessel and thermal shield Radiation values rescaled from LHC commissioning of sector 7-8 LHC linear heat loads (average values): 4.3 W/m vacuum vessel to thermal shield 0.2 W/m thermal shield to cold mass For SPL SCM: 33.0 TS from vacuum vessel K from thermal shield * C. Maglioni, LHC Project Note R. Bonomi TE-MSC-CMI SPL Seminar 2012

Mock-up test 16 R. Bonomi TE-MSC-CMI SPL Seminar 2012

Mock-up test 1.5 cavities, 2 DWTs, 1 intercavity support Cooled by LN2 Test of all possible cooling conditions No RF power 17 Validation of: Cavity supporting system Assembly realignment of cavities via vessel interface Alignment measuring device (OWPM) Thermal contractions DWT active cooling R. Bonomi TE-MSC-CMI SPL Seminar 2012

Mock-up test Estimated static heat load: Conduction from DWTs+feedthroughs: ~ 2 W (300 mg/s GN2) Radiation from vacuum vessel: ~ 10 W (rescaled from LHC) Example: evaporation of 1/4 of total LN2 volume (10 l out of 40 l) takes ~ 1.5 days 18 R. Bonomi TE-MSC-CMI SPL Seminar 2012

Thanks for your attention! SPL workspace: SPL docs on EDMS: R. Bonomi TE-MSC-CMI SPL Seminar 2012

Operating conditionValue Beam current/pulse lenght40 mA/0.4 ms beam pulse 20 mA/0.8 ms beam pulse cryo duty cycle4.11%8.22% quality factor10 x x 10 9 accelerating field25 MV/m Source of Heat LoadHeat 2K Beam current/pulse lenght40 mA/0.4 ms beam pulse20 mA/0.8 ms beam pulse dynamic heat load per cavity5.1 W20.4 W static losses<1 W (tbc) power coupler loss at 2 K<0.2 W HOM loss in cavity at 2 K<1<3 W HOM coupler loss at 2 K (per coupl.) <0.2 W beam loss1 W 2 K8.5 W25.8 W SPL operational conditions

Ideal vs. real refrigerator power Temperature level [K] IDEAL - Carnot [Wel/Wth] REAL [Wel/Wth] Efficiency wrt Carnot [%] < <30 R. Bonomi TE-MSC-CMI SPL Seminar 2012

(B) 1 Heat intercept 2K 300K x1x1 L 80K R. Bonomi TE-MSC-CMI SPL Seminar 2012

(C) 2 Heat intercepts 2K 300K 8K 80K L x1x1 x2x2 R. Bonomi TE-MSC-CMI SPL Seminar 2012

(D) He vapour cooling 300K 4.5K Q in g/s L attenuation factor R. Bonomi TE-MSC-CMI SPL Seminar 2012

SCM instrumentation

Burning coolant R. Bonomi TE-MSC-CMI SPL Seminar 2012