Feb. 21 st , 2017, WG-4 Design and fabrication status of RIKEN SC-Linac cryomodule K. Ozeki, O. Kamigaito, H. Okuno, N. Sakamoto, K. Suda, Y. Watanabe, K. Yamada RIKEN Nishina Center E. Kako, H. Nakai, K. Umemori KEK 1. Overview of RIKEN SC-Linac cryomodule 2. Magnetic characteristics NC → SC, SC → NC Performance of magnetic shield for RT at cryogenic temperature
1. Overview of RIKEN SC-Linac cryomodule Prototype: cryomodule which can mount two QWRs (tentatively, one QWR and one dummy cavity will be installed) K. Ozeki et al., LINAC16, TUPLR061 Vacuum vessel Thermal shield - Vacuum of QWR is isolated - 2 mm t Al - 77-K GM cryocooler CH-100LT (SHI) Helium buffer tank ~100 W@ 40 K (50 Hz) Dummy cavity Magnetic shield - 2 mm t permalloy Frequency tuner - Enfolding QWR and He jacket - Mark: 20 mG @ top part of QWR - Adjustment of gap length of QWR by distorting QWR in beam axial direction (MHI-MS, PCT/JP2016/54710, Feb. 18, JP Patent P5985011, 2016) He jacket Power coupler QWR - Disk-type double vacuum windows (40 K / RT) - Assumed Max. RF power: 10 kW
1. Overview of RIKEN SC-Linac cryomodule Prototype: cryomodule which can mount two QWRs (tentatively, one QWR and one dummy cavity will be installed) K. Ozeki et al., LINAC16, TUPLR061 Vacuum vessel Thermal shield - Vacuum of QWR is isolated - 2 mm t Al - 77-K GM cryocooler CH-100LT (SHI) Helium buffer tank ~100 W@ 40 K (50 Hz) Dummy cavity Magnetic shield - 2 mm t permalloy Frequency tuner - Enfolding QWR and He jacket - Mark: 20 mG @ top part of QWR - Adjustment of gap length of QWR by distorting QWR in beam axial direction (MHI-MS, PCT/JP2016/54710, Feb. 18, JP Patent P5985011, 2016) He jacket For Actual cryomodules, installation in He jacket is planned Power coupler QWR Performance test of magnetic shield (permalloy) for RT at cryogenic temperature - Disk-type double vacuum windows (40 K / RT) - Assumed Max. RF power: 10 kW
1. Overview of RIKEN SC-Linac cryomodule Feb. 17 th 10:35 Assembly of each component into cryomodule is now in progress Cooling test: next month
2. Magnetic characteristics VTs at KEK 1) Jun. 30 th , 2016 2) Sep. 7 th , 2016 3) Oct. 20 th , 2016 ● One fluxgate installed 4) Feb. 1 st , 2017 ● Performance test of magnetic shield for RT at cryogenic temperature ● Two fluxgates installed
VT3 on Oct. 20 th , 2016 ● One fluxgate installed Temperature reference points Si-diode (accuracy: ± 0.25 K) General setup Outer torus Magnetic shield (RT) Cryostat Stem root Magnetic field in vertical direction Stem QWR Side port (attached to blank flange) Lower welded spot (between bottom pan and trunk)
VT3 on Oct. 20 th , 2016 Si-diode Fluxgate
VT3 on Oct. 20 th , 2016 Si-diode Fluxgate NC → SC
VT3 on Oct. 20 th , 2016 Si-diode Fluxgate NC → SC Radiation shield was set on the pit: Δ H ~ 1 mG
VT3 on Oct. 20 th , 2016 Si-diode Fluxgate NC → SC Q-measurement: no influence on H Radiation shield was set on the pit: Δ H ~ 1 mG
VT3 on Oct. 20 th , 2016 Si-diode Fluxgate NC → SC Q-measurement: no influence on H SC → NC Radiation shield was set on the pit: Δ H ~ 1 mG
VT3 on Oct. 20 th , 2016 Si-diode Fluxgate NC → SC Q-measurement: no influence on H Δ H ~ 1.5 mG SC → NC Radiation shield was set on the pit: Δ H ~ 1 mG
VT3 on Oct. 20 th , 2016 Dotted lines: temperature got lower / higher than 9.2 K at each point (accuracy: ± 0.25 K) NC → SC SC → NC FG NC SC SC NC H got higher until the trunk of QWR partially H jumped up when the lower part of transited from NC to SC. Then, H got lower QWR transited from SC to NC. to the level lower than initial H .
VT4 on Feb. 1 st , 2017 ● Performance test of magnetic shield for RT at cryogenic temperature ● Two fluxgates installed Temperature reference points Si-diode (accuracy: ± 0.25 K) Directly beneath General setup opening of shield Outer torus → not fully shielded Magnetic shield (Cryo-temp.) Magnetic shield (RT) Cryostat Stem root Cavity trunk Stem QWR + Magnetic field He jacket in vertical direction Side port (attached to blank flange) Coupler port
VT4 on Feb. 1 st , 2017 Si-diode Fluxgate NC → SC Q-measurement: no influence on H SC → NC Offset? Radiation shield was set on the pit: very small shift in H
VT4 on Feb. 1 st , 2017 Dotted lines: temperature got lower / higher than 9.2 K at each point (accuracy: ± 0.25 K) NC → SC SC → NC FGs NC SC SC NC H at both positions showed No apparent behavior similar tendency as VT3
VT4 on Feb. 1 st , 2017 Performance shift of permalloy for RT (OHTAMA) at cryogenic temperature FG-inner FG-outer ● No problems in using permalloy for RT at cryogenic temperature ● Discrepancy in H between before and after VT (Seems to be attributed to the element other than permalloy ← cf: VT3)
Summary ● Present status of cryostat - Assembly of QWR and other components into one cryomodule is now in progress. - Cooling test will be performed in next month. ● Magnetic characteristics - H around top of QWR were measured. NC → SC: H gets higher transiently, and then gets lower than initial H. SC → NC: jump up in H / no apparent behavior (unclear ?) Discrepancy in H between before and after VT. ● Performance test of permalloy for RT - Permalloy for RT seems to be able to be used at cryogenic temperature without any problems.
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