Low Beta Cryomodule Development at Fermilab Tom Nicol March 2, 2011
Concepts of SC CW 3GeV, 1mA Linac H - gun RFQ MEBT SSR0 SSR1 SSR2 β=0.6 β=0.9 ILC RT (~15m) 325 MHz 2.5-160 MeV 650 MHz 0.16-2 GeV 1.3 GHz 2-3 GeV Section Freq, MHz Energy(MeV) Cav/mag/CM Type SSR0 ( G =0.11) 325 2.5-10 26 /26/1 SSR, solenoid SSR1 ( G =0.22) 325 10-32 18 /18/ 2 SSR, solenoid SSR2 ( G =0.42) 325 32-160 44 /24/ 4 SSR, solenoid LB 650 ( G =0.61) 650 160-520 42 /21/ 7 5-cell elliptical, doublet HB 650 ( G =0.9) 650 520-2000 96 / 12/ 12 5-cell elliptical, doublet ILC 1.3 ( G =1.0) 1300 2000-3000 64 / 8/ 8 9-cell elliptical, quad Initial configuration. Now changed to reduce gradient in HE650 N.Solyak, Project-X Linac design FNAL PrX Retreat, Nov.2, 2010 2
Project X optics layout (version 3.7.4) TTC WG-2 - March 2, 2011 Page 3
SSR cryomodule configurations (version 3.7.4) (18 / 18) (10 / 10) (10 / 5) TTC WG-2 - March 2, 2011 Page 4
Front end optics (version 3.7.4) TTC WG-2 - March 2, 2011 Page 5
Segmentation features Coarse segmentation Large diameter interconnect bellows at each end of each module. All internal piping connection from one module to another are made inside the interconnect region, usually by a bellows. Continuous insulating vacuum space (at least between vacuum breaks). Fine segmentation One or more cryogenic distribution boxes at each module. The only direct connection between modules is the beam tube. Internal cold-to-warm transitions required at each end of each beam tube. TTC WG-2 - March 2, 2011 Page 6
Considerations Inter-cavity spacing between cryomodules. Alignment of elements inside individual cryomodules (inter-cryomodule segmentation). Warm diagnostics requirements. Total cryomodule heat load (affects heat exchanger size). Pressure relief size and frequency. Cooldown and warm-up time. Cost, including interconnects, feed cans, transfer lines, tunnel length, etc. Cryomodule pipe sizes. Technical risks in cryomodule design. Cryomodule installation, maintenance, and replacement time and effort. Considerations pertain to both cryo and vacuum segmentation. The type and degree of segmentation will likely be driven by requirements, not the other way around. TTC WG-2 - March 2, 2011 Page 7
SSR cavity and cryomodule assumptions Fine segmentation in all SSR sections, i.e. each cryomodule is selfcontained. Cavities and solenoids operate at 2 K. 2 K heat exchanger in each cryomodule. Cavity string supported by warm strongback. Conduction cooled current leads for all magnet coils. Cavity MAWP = 2.5 bar warm, 4 bar cold. Button BPM s between each cavity and solenoid. Cavities and solenoids individually aligned. No adjustment after final assembly into the cryomodule, but verifiable via optical windows. Warm magnetic shield inside vacuum vessel wall capable of reducing residual field to 10 T. Cold magnetic shield on each solenoid. TTC WG-2 - March 2, 2011 Page 8
Initial solenoid and cavity mounting scheme Cavity and solenoid mounted on separate supports. Strongback Becomes cumbersome when element spacing decreases, as in SSR0. TTC WG-2 - March 2, 2011 Page 9
SSR0, solenoid, and BPM assembly 610 mm Solenoid is the same one used in the HINS front end, RT section. 2 K operation gives additional field and margin needed for SSR0 and SSR1 cryomodules. Reduced element spacing, especially for SSR0 made the original scheme less attractive. TTC WG-2 - March 2, 2011 Page 10
SSR1, solenoid, and BPM assembly 750 800 mm TTC WG-2 - March 2, 2011 Page 11
SSR0 cavity string BPM C/W transition Strongback Support post TTC WG-2 - March 2, 2011 Page 12
Cavity string, piping, leads, etc. 2-phase header Solenoid and shield Heat exchanger Check valve (may omit) Current lead assembly C/W transition Solenoid pedestal TTC WG-2 - March 2, 2011 Page 13
Prototype cryomodule Heat exchanger and relief line Cryogenic feeds and controls Cavity vacuum pumpout Current lead assemblies RF input couplers Alignment viewports TTC WG-2 - March 2, 2011 Page 14
Domed end alternative TTC WG-2 - March 2, 2011 Page 15
Prototype cryomodule flat ends (SSR0 cavities shown) TTC WG-2 - March 2, 2011 Page 16
Prototype cryomodule domed ends (SSR0 cavities shown) TTC WG-2 - March 2, 2011 Page 17
Prototype cryomodule flat ends (SSR0 cavities shown) TTC WG-2 - March 2, 2011 Page 18
Prototype cryomodule domed ends (SSR0 cavities shown) TTC WG-2 - March 2, 2011 Page 19
SSR estimated heat loads SSR0 (qty 1) Each unit Mult Total 18 cavities, 18 solenoids 70 K 4.5 K + 2 K 70 K 4.5 K + 2 K Input coupler static 2.37 0.67 18 42.7 12.1 Input coupler dynamic 0 0.25 18 0.0 4.5 Cavity dynamic load 0 0.5 18 0.0 9.0 Support post 2.76 0.41 18 49.7 7.4 Conduction lead assembly 36.8 14.44 18 662.4 259.9 MLI (total 70 K +2 K) 62.2 2.9 1 62.2 2.9 Cold to warm transition 0.72 0.09 2 1.4 0.2 Total 818.4 295.9 SSR1 (qty 2) Each unit Mult Total 10 cavities, 10 solenoids 70 K 4.5 K + 2 K 70 K 4.5 K + 2 K Input coupler static 2.37 0.67 10 23.7 6.7 Input coupler dynamic 0 0.25 10 0.0 2.5 Cavity dynamic load 0 0.8 10 0.0 8.0 Support post 2.76 0.41 10 27.6 4.1 Conduction lead assembly 36.8 14.44 10 368.0 144.4 MLI (total 70 K +2 K) 48.1 2.2 1 48.1 2.2 Cold to warm transition 0.72 0.09 2 1.4 0.2 Total 468.8 168.1 SSR2 (qty 4) Each unit Mult Total 10 cavities, 5 solenoids 70 K 4.5 K + 2 K 70 K 4.5 K + 2 K Input coupler static 2.37 0.67 10 23.7 6.7 Input coupler dynamic 0 0.25 10 0.0 2.5 Cavity dynamic load 0 2.9 10 0.0 29.0 Support post 2.76 0.41 10 27.6 4.1 Conduction lead assembly 36.8 14.44 5 184.0 72.2 MLI (total 70 K +2 K) 48.1 2.2 1 48.1 2.2 Cold to warm transition 0.72 0.09 2 1.4 0.2 Total 284.8 116.9 Summary Each unit Mult Total SSR0, SSR1, SSR2 70 K 4.5 K + 2 K 70 K 4.5 K + 2 K SSR0 818.4 295.9 1 818.4 295.9 SSR1 468.8 168.1 2 937.6 336.2 SSR2 284.8 116.9 4 1139.2 467.7 Total 2895.2 1099.8 Notes: 1. Assume 2 pairs of 50 A and 1 pair of 200 A leads per solenoid. 2. Cavity dynamic loads from N. Solyak. TTC WG-2 - March 2, 2011 Page 20
SSR1 cavity 2 cavities in-house, one from Zanon, one from Roark. 2 are in-process in India. An order for 10 more is in-process at Roark/Niowave. TTC WG-2 - March 2, 2011 Page 21
Dressed SSR1 Cavity and Tuner Parts for 2 helium vessels are in-house, one of which is welded. One prototype tuner is being tested warm. TTC WG-2 - March 2, 2011 Page 22
Support post 2 supports built to date, one proof-tested to failure, one installed in the test cryostat. TTC WG-2 - March 2, 2011 Page 23
Input coupler Coaxial design, adjustable, 76.9 mm outer/33.4 mm inner, two disk-type ceramic windows. 3 couplers are in-house and tested. One currently installed in test cryostat. Design modifications in-process to reduce weight. TTC WG-2 - March 2, 2011 Page 24
Alternate design input coupler TTC WG-2 - March 2, 2011 Page 25
Conduction cooled current lead assembly Modeled after similar leads designed at CERN. 4 leads at 50 A, 2 leads at 200 A. Thermal intercepts at 80 K and 5 K. Sample leads currently being fabricated to verify thermal performance of conductor and intercepts. TTC WG-2 - March 2, 2011 Page 26
SSR0 BPM assembly 270 mm 205 mm Beam Cavity end 4-1/2 fixed Conflat 1-1/2 OD, 30 mm ID tube 4-1/2 rotatable Conflat TTC WG-2 - March 2, 2011 Page 27
Test cryostat installed in MDB TTC WG-2 - March 2, 2011 Page 28
325 MHz steady-state results Number of cavities vs. 2-phase pipe size Small 2-phase pipe OK for steady-state SSR0 SSR1 and SSR2 From Tom Peterson TTC WG-2 - March 2, 2011 Page 29
325 MHz steady-state results Number of cavities vs. 2-phase pipe size Emergency venting of 10 cavities results in 2 bar pressure drop Emergency venting of 8 cavities results in 1 bar pressure drop For mechanical space reasons we would like to use a 5-inch OD tube in our 325 MHz CM. The practical limit then is 8 cavities in series for emergency venting flow. From Tom Peterson TTC WG-2 - March 2, 2011 Page 30
325 MHz 2-Phase pipe conclusion Steady-state flow requirement is relatively low. 4 cm ID is adequate to keep a low helium vapor velocity (< 5 m/sec) with over 20 cavities in series, such as one long SSR0 cryomodule (neglecting cross-section occupied by liquid, so we have to add to the diameter for a liquid level). Venting for loss of cavity vacuum determines 2-phase pipe size. A 3 inch air inlet hole implies roughly a 14 cm 2-phase pipe and a 19 cm vent line. Basically 5-6 inch and 8 inch diameter, respectively. Prototype SSR cryomodule will incorporate these pipe sizes even though they would not be required for this small cryomodule alone. TTC WG-2 - March 2, 2011 Page 31
FRIB bathtub design cryomodule TTC WG-2 - March 2, 2011 Page 32
Status and plans Optics design is in-process and seems to be converging. SSR1 cavity design complete. SSR0 nearly complete. SSR2 in-process. Helium vessel designs for all are in-process (1 st generation SSR1 helium vessel will not be used in prototype cryomodule). Prototype cryomodule design in-process. It will contain 4 cavities and 4 solenoids, either SSR0 or SSR1. Final configuration to be determined. Functional specification for the prototype is complete and those for the production SSR cryomodules are in-process. Many sub-component designs are complete or nearly so. Strongback Support post Input coupler Current lead assembly First generation tuner BPM Need to work out assembly procedure details, especially for the longest cryomodules. Test cryostat for single, dressed cavity tests is installed. A 2 K conversion is being designed. Weighing pros and cons of adopting the bathtub style cryomodule. TTC WG-2 - March 2, 2011 Page 33