Commissioning experience from LIPAc in Japan 8 th

Commissioning experience from LIPAc in Japan 8 th Open Collaboration Meeting on Superconducting Linacs for High Power Proton Beams (SLHi. PP-8) Uppsala, June 13 th 2018 J. Marroncle – CEA Saclay

DSM/Irfu, CEA Saclay B. Bolzon, N. Chauvin, S. Chel, F. Harrault, R. Gobin, J. Marroncle, F. Senée CIEMAT, Madrid D. Jimenez, J. M. Carmona, I. Podadera, J. A. Valera, M. Weber F 4 E (Fusion for Energy) – Garching P. Y. Beauvais, P. Cara, H. Dzitko, A. Jokinen, I. Moya, R. Heidinger IFMIF-EVEDA – Project team - Rokkasho J. Knaster, A. Marqueta, K. Nishiyama , Y. Okumura, G. Pruneri, F. Scantamburlo INFN, Legnaro L. Bella, M. Communian, E. Fagotti, F. Grespan, A. Pisent National Institutes for Quantum and Radiological Science and technology, Rokkasho T. Akagi, R. Ichimiya, A. Ihara, A. Kasugai, T. Kitano, M. Komata, K. Kondo, K. Sakamoto, T. Shinya, M. Sugimoto Special thanks to these colleagues who helped me a lot while preparing this talk: B. Bolzon, P. Y. Beauvais, N. Chauvin, S. Chel, F. Senée

Outlook • IFMIF, LIPAc… in few words • Commissioning Ø Injector Ø High energy section of the LIPAc 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 3

IFMIF International agreement of the “Broader Approach” (Japan + Europe in Feb. 2007); BA = IFMIF/EVEDA + IFERC + JT 60 -SA IFMIF*: International Fusion Material Irradiation Facility for testing materials submitted to very high neutron fluxes for future Fusion Reactors. Very huge neutron source: flux ~ 1018 neutrons/m 2/s Lithium Target 25 mm thick, 15 m/s beam profile = 20 x 5 cm 2 Test Cell H M 2 cw accelerators, 2 x 125 m. A, 2 x 5 MW L nuc. reactions 7 Li(d, 2 n)7 Be RFQ 5 Me. V deuteron source 140 m. A, 100 ke. V 2018/06/13 6 Li(d, n)7 Be 6 Li(n, T)4 He Superconducting Linac 40 Me. V (Half Wave Resonators) LIPAc Commissioning - SLHi. PP 8 - JM High > 20 dpa/y 0. 5 l Medium > 1 dpa/y 6 l Low 1 dpa/y > 8 l 4

LIPAc: Linear IFMIF Prototype Accelerator Validation phase: prototype accelerator ➝ LIPAc RF = 175 MHz LIPAc = 125 m. A cw, 9 Me. V, 1. 125 MW 12. 5 k. W 100 ke. V 625 k. W 5 Me. V 1125 k. W 9 Me. V Beam Dump ion source Beam Extraction LEBT RFQ MEBT Sc HWR-Linac HEBT ECR source 2. 45 GHz 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 5

contribution to LIPAc Most accelerator components designed and constructed in Europe Installed and commissioned in Rokkasho Injector + LEBT CEA Saclay Diagnostics CEA Saclay CIEMAT Madrid 2018/06/13 RFQ MEBT INFN Legnaro CIEMAT Madrid QST Cryoplant CEA Saclay SRF Linac CEA Saclay CIEMAT Madrid HEBT CIEMAT Madrid BD CIEMAT Madrid 36 m RF Power CIEMAT Madrid CEA Saclay SCK Mol Building Auxiliary System Control system Installation QST LIPAc Commissioning - SLHi. PP 8 - JM 6

General Plan for LIPAc commissioning B A Phase A: injector Inst. & commissioning 2014 - end 2017 • H+ & D+ (low dc) Phase B: RFQ Inst. & commissioning MEBT + DP + LPBD (0. 1% cw) 2017 – fall 2018 • Assembling RFQ module, bead pull… • Moving RFQ to nominal location • Commissioning with MEBT+D-Plate just started, in progress • H+ & D+ (low dc) 2018/06/13 C D Phase C: SRF + HEBT + LPBD / BD commissioning, but 0. 1% cw end 2018 – 1/2020 • SRF cryomodule assembling at Rokkasho • Installation SRF + HEBT + BD • H+ & D+ (low dc) Phase D: LIPAc Up to 3/2020 • H+ & D+ beams, up to cw. LIPAc Commissioning - SLHi. PP 8 - JM 7

Injector commissioning Ion source + LEBT 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 8

Injector challenges Emax = 100 ke. V & ID+ ∼ 140 m. A High Space Charge: shorten the LEBT length for minimizing emittance growth Limitation of the number of diagnostics: 1 ACCT and no DCCT Optimization of the LEBT configuration: specific chamber used for several diagnostics AND vacuum equipment High average power: around 15 k. W at 100% d. c. : Ensure an efficient water cooling of interceptive devices (Faraday cup, EMU shielding) Need to implement cooling circuits on parts collecting only few % of the beam (electrodes) Activation: shall be mastered to allow access for repair/improvement Operation with proton beam at same Perveance (same SC effect) for accelerator debugging EProton = 50 ke. V & IProton = 70 m. A Minimizing the duration of runs of D+ at high current and duty cycle and of course, whatever the constraints the performances remain unchanged: Normalized transverse emittance < 0. 30 π·mrad·mm Twiss parameters ensuring a good matching to the RFQ crucial to prevent from excessive losses in the RFQ Note: RFQ cone: φ=12 mm, angle ± 8° 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 9

LEBT diagnostics - Particle loss: thermocouples on the last grounded electrode - SC compensation measurement: 1 FGA (4 Grid Analyzer) - Beam current: 1 ACCT (at RFQ entrance -> transmission) 1 "Faraday Cup”, Beam Stopper ➝ Calorimetric measurements (FC, BS) - Emittance (Allison): 4 positions for 1 Emittancemeter EMU - Transverse beam profiles (fluorescence): 4 CID cameras, 1 CCD - Beam fraction species (Doppler): 1 deported spectrometer with a fiberscope Note: a beam chopper is installed between the 2 solenoids 1 st Diag. Chamber 2 nd DC (removed for RFQ installation) (permanent) ECR source chopper EMU Fiberscope + remote 2. 45 GHz 4 CID (H/V) acc. spectrometer column Dedicated diagnostic box for beam characterization during LEBT commissioning BS FGA BS ACCT 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM CCD (V) or intensified CID (V) 10

Emittance: Allison scanner 100% d. c. mode ➝ 15 k. W (Max) Emittance measurement made on LIPAc injector (CEA Saclay, 08/2012) • with a proton beam to avoid injector activation • Ep = 50 ke. V and 70 m. A ⇒ εx = 0. 29 π·mm·mrad RFQ acceptance εx, y = 0. 30 π·mm·mrad (0. 25 specification) Data taken during acceptance tests at CEA Saclay, August 2012 LIPAc injector (Proton) 0. 29 π·mm·mrad 2018/06/13 2012 – D+ 100 ke. V 10%cw 0. 20 π·mm·mrad LIPAc Commissioning - SLHi. PP 8 - JM Designed at CEA Saclay 11

Allison scanner principle intensity thanks to F. Senée y’ 1 Angle y’ y’ 2 y’ 3 Angle y’ y’ 3 y 1 y’ 2 Beam Axis y’ 2 y’ 1 y 3 y’ 3 y 1 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM y 2 y 3 12

Doppler A fiberscope (20 m long Fujikura radiation hard) is plugged on the pipe chamber and to a remote spectrometer set in a shielding area to feed it with fluorescence Dα Balmer ray (interaction beam/RG). D+ beam: 150 m. A / 115 m. A (BS) – 100 ke. V – 3%cw 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 13

Commissioning steps 11/2012: acceptance test at Saclay Phase A 3 • July 2017: 2 week D+ (not published) 9/2017: adjustment of accelerator column Phase B 0 (RFQ already installed) • 12/17 -2018: 2 weeks D+ (several H+) 12/18 to 01/2019 new D+ campaign to work in cw is foreseen (6 to 8 weeks) Phase A 2: Phase A 1 (~20 w) • Nov. -Dec. 2014: 5 week H+ • April-June 2015: 5 week H+ • July-Sept. 2015: 0. 5/9 week H+ /D+ Phase A 2 (~21 w) • Sept. -Dec. 2015: 4/3. 5 weeks H+/D+ • Jan. -June 2016: 8. 5 weeks H+ • Oct. -Nov. 2016: 5 weeks D+ Phase A 1: Y. Okumura, et al. , Rev. Sci. Instrum. 87 (02) (2016) A 739 K. Shinto, et al. , Rev. Sci. Instrum. 87 (02) (2016) A 727 R. Gobin, et al. , Rev. Sci. Instrum. 87 (02) (2016) A 726 B. Bolzon, et al. , IBIC 2015, TUPB 008 N. Chauvin et al. , “beam commissioning of the linear IFMIF Prototype Accelerator Injector: measurements and simulations’, IPAC 13, Shanghai, China. A 3 2018/06/13 B. Bolzon, et al. , IPAC 2016, WEPMY 033 B. Bolzon, et al. , ECRIS 2016, WECO 01 (also phase A 1) B. Bolzon, et al. , Fusion Eng. Des. (2018) (also A 1/A 3) https: //doi. org/10. 1016/j. fusengdes. 2018. 04. 128 L. Bellan et al. , Source and LEBT beam preparation for IFMIFEVEDA RFQ, LINAC 2016, TUPRC 005, East Lansing, MI, USA A 1 LIPAc Commissioning - SLHi. PP 8 - JM A 2 14

Few results for A 1 D+ beam: 91 m. A – 100 ke. V –cw D+ D+ beam: 105 m. A – 100 ke. V – 9. 5% D 3 + D 2 + Φplasma=10 mm D+ beam: 155/125 m. A – 100 ke. V – 10% After background subtraction EMU 81% D+ / similar to Doppler This agreement does not work for proton beam at 50 ke. V! TBI 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM No emittance improvement evidence after Kr injection 15

Few results for A 2 D+: 100 ke. V, 3% L. Bellan (INFN Legnaro) Sol. 2 (A) compromise: end 2016 EMU located downstream the cone entrance divergence Sol. 1 (A) strong focusing area During the long commissioning process allowing to counteract many problems, few matching difficulties between experimental and calculated variables appeared… discrepancy between injector electrodes and the design before correction design were measured and fixed on 09/2017 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 16

Once electrodes fixed (12/2017) N. Chauvin, meeting at Rokkasho, Dec. 2017 D+ 165 m. A, 100 ke. V, 3% D+, 100 ke. V, 5% (2 ms/40 ms) Sol 1 275 A big improvement of Emittance, clearly under 0. 25 π·mrad·mm Summary Report to the BA SC #22 (26/04/2018) “The beam emittance values now reliably meet and even exceed the specifications in pulsed operation. They are also coherent with the beam simulations performed by CEA and INFN” 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 17

Few lessons learned • Importance to develop relevant beam dynamics simulations, starting from particle extraction with respect to the real design • Accurate accelerator alignment: it is even more relevant for the LEBT made of 2 solenoids which slightly rotate the beam. Misalignment implies to correct with steerers and tuning becomes then difficult to interpret and implement! • Plasma chamber must have a high cleanliness level to generate numerous e-, H+ or D+… To be banned: oil pumps! Indeed hydrocarbons must pollute the plasma chamber generating electric sparks… compromising high electric field behavior as well as its stability • Space Charge: no significant effect has been observed by injecting Kr in our conditions. Note that Kr may neutralize beam particles, decreasing the beam intensity! • Keep tracks of all modifications or actions done on the system. • H/2 and D are similar in term of SC, but not similar at the exit of the plasma chamber (extraction system can not be the same!) commissioning • Not easy to extrapolate pulsed to cw results with stable beam characteristics 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 18

Next commissioning phases 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 19

LIPAc diagnostics Glossary: ACCT: AC Current Transformer BLo. M: Beam Loss Monitor RGBLM: Residual Gas Bunch Length Monitor BPM: Beam Position Monitor DCCT: DCBeam Current BLo. M: Loss. Transformer Monitor FC: Faraday BPM: Beam. Cup Position Monitor FFC: Fast Faraday Cup CT: Current Transformer FFC: Fast. Current Faraday. Transformer Cup FCT: FPM: Fluorescence Profiler Monitor IPM: Ionization Profiler Monitor FPM: Fluorescence Profile Monitor µLo. M: Micro micro. Loss Monitor µLo. M: ACCT + DCCT IPM SEM Grids (1 m from slits) D-Plate 2 Slits (Emittance) RGBLM: Residual Gas Bunch Length Monitor FFC 2 BPMs (striplines) RGBLM 1 BPM (Stripline) FPM Emittance meter Species fraction measurement FC ∼ 20 BLo. Ms for the whole end-accelerator ACCT 4 Profilers (CCD camera) ACCT + FCT ACCT 3 x 8 µLo. M 4 grids analyser 2 BPM 4 BPM (striplines) IPM 9 Me. V 5 Me. V 100 ke. V SEM Grids 8 BPM (cryo) 3 BPM 1 Slit (E. spread) FPM 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 20

Diagnostic Plate Transverse emittance • 2 horizontal and vertical slits (100 or 200µm) • Steerers HV + SEM grids Beam energy and beam position • 3 BPM (Strip-lines) Bunch length • • Beam / residual gas ionization electron extraction under E field Magnetic chicane (mono-energetic) MCP detection (To. F wrt RF signal) Transverse profile monitors • 1 IPM + 2 FPM for X&Y profiles Beam current • ACCT+DCCT (DP) Beam Loss Monitors • more than 4 ICs 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 21

2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 22

LIPAc commissioning sketches top view sketches LPBD < 0. 1% cw Phase B (0. 1% cw) Phase C (0. 1% cw…) Phase D (up to 100% cw) 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 23

RFQ & LEBT commissioning – Phase B duty cycle < 0. 1% cw Rough expectations • B 1 beam line characterization for H+ up to 8/2018 beam passing through RFQ, MEBT, diagnostic tests… • Before end 2018: Tests with maximum length pulses D+ beams short length (10µs) and back to H+ Activation tests 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 24

SRF Linac commissioning – Phase C duty cycle < 0. 1% cw Rough expectations • HEBT & BD installation up to 1/2019 • Ready to take beam (low power) SRF Linac will be installed in the vault by spring 2019 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 25

LIPAc commissioning – Phase D duty cycle: 0. 1% up to cw Rough expectations • SRF Linac - 2/2018: first components received at Rokkasho fall 2018: assembling start spring 2019: installation in the vault and conditioning 1/2020: ready for beam operation • Beam up to 31/03/2020 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 26

NPM summary Commissioning of LIPAc is a long way Injector commissioning Ø Almost finished with correct TWISS parameters and quite low emittance compliant to RFQ Ø Another period is foreseen increase the duty cycle in D+… up to cw Higher energy part Ø RFQ commissioning in starting phase Ø High power BD (able to handle 1. 1 MW) installation will start soon Ø SRF Linac assembly in Rokkasho will start by fall 2018 Ready for commissioning on beginning 2020 End March 2020 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 27

spares 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 28

Pulse length monitor 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 29

Transversal emittance at high energy SEM grids (plan de fils) fentes beamlet X Déviateur beam axis ∆X 2018/06/13 LIPAc Commissioning - SLHi. PP 8 - JM 2, 25 1, 50 0, 75 X 1 X 2 X 3 X 4 X 5 X 6 X 7 X 8 0 ∆2 ∆1 ∆3 30

Radiation background LIPAc radiation background study New shielding (polyethylene disks, plates…) ➟ neutrons Fluence, calculated over 6 months cw Point # 5 15 25 145 115 85 n/cm 2/s 7 108 6 108 5 108 4 107 6 106 4 106 Fluence n/cm 2 1 1016 8 1015 6 1014 9 1013 7 1013 125 105 115 95 75 55 145 45 135 35 25 15 5 65 85 A. Marchix – January 2012 (only BD) Old shielding (concrete wall…) ➟ neutrons, γ Fluence, calculated over 6 months cw Point # Radius (cm) 1 2 3 3 12. 5 37. 5 Neutron (n/cm 2) 2 1015 9 1013 3 1014 6 1012 1 1013 γ (n/cm 2) 3 1014 4 1013 5 1013 2 1012 3 1012 2 Old shielding 1 UNED study (~2008) Rokkasho meeting, March 2012 - PY Beauvais 31