Low Beta Cryomodule Development at Fermilab Tom Nicol

Low Beta Cryomodule Development at Fermilab Tom Nicol March 2, 2011

Concepts of SC CW 3 Ge. V, 1 m. A Linac H-gun RFQ SSR 0 SSR 1 SSR 2 β=0. 6 MEBT 325 MHz 2. 5 -160 Me. V RT (~15 m) Section β=0. 9 ILC 650 MHz 0. 16 - 1. 3 GHz 2 -3 Ge. V 2 Ge. V Freq, MHz Energy(Me. V) Cav/mag/CM Type SSR 0 ( G=0. 11) 325 2. 5 -10 26 /26/1 SSR, solenoid SSR 1 ( G=0. 22) 325 10 -32 18 /18/ 2 SSR, solenoid SSR 2 ( 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 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 HE 650 N. Solyak, Project-X Linac design FNAL Pr. X 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 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 m. 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 SSR 0. TTC WG-2 - March 2, 2011 Page 9

SSR 0, 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 SSR 0 and SSR 1 cryomodules. TTC WG-2 - March 2, 2011 Reduced element spacing, especially for SSR 0 made the original scheme less attractive. Page 10

SSR 1, solenoid, and BPM assembly 750 – 800 mm TTC WG-2 - March 2, 2011 Page 11

SSR 0 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 Heat exchanger Check valve (may omit) Solenoid and shield Current lead assembly C/W transition TTC WG-2 - March 2, 2011 Solenoid pedestal Page 13

Prototype cryomodule Heat exchanger and relief line Cryogenic feeds and controls Cavity vacuum pumpout Current lead assemblies RF input couplers TTC WG-2 - March 2, 2011 Alignment viewports Page 14

Domed end alternative TTC WG-2 - March 2, 2011 Page 15

Prototype cryomodule – flat ends (SSR 0 cavities shown) TTC WG-2 - March 2, 2011 Page 16

Prototype cryomodule – domed ends (SSR 0 cavities shown) TTC WG-2 - March 2, 2011 Page 17

Prototype cryomodule – flat ends (SSR 0 cavities shown) TTC WG-2 - March 2, 2011 Page 18

Prototype cryomodule – domed ends (SSR 0 cavities shown) TTC WG-2 - March 2, 2011 Page 19

SSR estimated heat loads SSR 0 (qty 1) Each unit 18 cavities, 18 solenoids 70 K 4. 5 K + 2 K 2. 37 0. 67 Input coupler dynamic 0 Cavity dynamic load Total 70 K 4. 5 K + 2 K 18 42. 7 12. 1 0. 25 18 0. 0 4. 5 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. 2 818. 4 295. 9 Input coupler static Total SSR 1 (qty 2) Each unit 10 cavities, 10 solenoids 70 K 4. 5 K + 2 K 2. 37 0. 67 Input coupler dynamic 0 Cavity dynamic load Mult Total 70 K 4. 5 K + 2 K 10 23. 7 6. 7 0. 25 10 0. 0 2. 5 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. 2 468. 8 168. 1 Input coupler static Total SSR 2 (qty 4) Each unit 10 cavities, 5 solenoids 70 K 4. 5 K + 2 K 2. 37 0. 67 Input coupler dynamic 0 Cavity dynamic load 0 Input coupler static Mult Total 70 K 4. 5 K + 2 K 10 23. 7 6. 7 0. 25 10 0. 0 2. 5 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. 2 284. 8 116. 9 Total Summary Each unit SSR 0, SSR 1, SSR 2 70 K 4. 5 K + 2 K SSR 0 818. 4 295. 9 SSR 1 468. 8 168. 1 SSR 2 Total TTC WG-2 - March 2, 2011 Mult 284. 8 Mult 116. 9 4. 5 K + 2 K 1 818. 4 295. 9 2 937. 6 336. 2 4 Total 70 K 1139. 2 467. 7 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. Page 20

SSR 1 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 SSR 1 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

SSR 0 BPM assembly 270 mm 205 mm Beam 4 -1/2” fixed Conflat TTC WG-2 - March 2, 2011 Cavity end 1 -1/2” OD, 30 mm ID tube 4 -1/2” rotatable Conflat 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 SSR 0 SSR 1 and SSR 2 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. TTC WG-2 - March 2, 2011 From Tom Peterson 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 SSR 0 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. SSR 1 cavity design complete. SSR 0 nearly complete. SSR 2 in-process. Helium vessel designs for all are in-process (1 st generation SSR 1 helium vessel will not be used in prototype cryomodule). Prototype cryomodule design in-process. It will contain 4 cavities and 4 solenoids, either SSR 0 or SSR 1. 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