Report on PIAVE G. Bisoffi

Transcription

1 Report on PIAVE G. Bisoffi International Scientific Committee, Legnaro February 10th, 2005

2 Context: Upgrade of the LNL Nuclear Physics Facility 3. CRYOGENIC SYSTEM UPGRADE 5. ALPI Energy Upgrade LOW BETA CAVITIES UPGRADE PIAVE Commissioning 1. ECRIS Operation 1

3 From Tandem to PIAVE as ALPI Injector XTU-tandem: 15 MV, 30-8 MeV/u, H- 127 I beams ALPI: V eq ~ 35 MV, 12 C 127 I E/A [MeV/u] ALPI Output with the two Injectors Tandem Tandem+ALPI (G-F) (1-10 pna) PIAVE+ALPI ( pna) New Injector A ) MORE CURRENT 2) LARGER MASSES 3) MORE BEAM TIME AVAILABLE (TWO INJECTORS)

4 Context: Upgrade of the LNL Nuclear Physics Facility 3. CRYOGENIC SYSTEM UPGRADE 5. ALPI Energy Upgrade LOW BETA CAVITIES UPGRADE PIAVE Commissioning 1. ECRIS Operation 1

5 The Whole LNL Programme since Oct ECRIS: to be put back in operation after the fire of February PIAVE Accelerator: to be assembled, tested for cryogenics and RF-superconductivity, beam commissioned 3. Lower β ALPI branch: to provide efficient refrigeration 4. Lower β ALPI branch: to lock the 80 MHz frequency stably versus liquid He pressure variations (upgrade of mechanical tuners) 5. ALPI Energy Upgrade: increase overall acceleration through change of the cavity SC layer (completed by October 2003)

6 June 2004 Dec 2004 Schedule shown on October 23, 2003

7 PIAVE: present status SRFQ ECR + LEBT QWR ALPI 12/2004: 1.3 µa,20mev 16 O +3 (pilot beam) (transmission 40 %) 12/2004: 100 na,70 MeV 132 Xe 18+

8 New Injector: the superconducting RFQs ECRIS CRYO-PLANT LEBT SRFQs HEB to ALPI CRYOSTAT QWRs

9 By January 2004: all destroyed components replaced, all others checked February 11, 2004: ECRIS plasma switched on, extraction of 12 eµa of a 16 O 4+ beam February 27, 2004: beam extraction from 350 kv platform ( ) Beam times for PIAVE: March-Apr 2004, Sep- -Dec 2004 Development of ion species (rest of the time) The ECR Ion Source

10 Typical ion species development in 2004 on the ECRIS on the HV platform Element Charge State Current (ena) 63 Cu (a) 84 Kr Ag (a) 120 Sn (b) 132 Xe Pr (b) (a) M. Cavenago, T. Kulevoy and S. Petrenko, Rev. Sci. Instr. 75, 4934 (2004) (b) M. Cavenago, T. Kulevoy and S. Petrenko, Proc. of EPAC2004 (eds. J. Poole et al.), 1303 (2004) The ECR Ion Source

11 New Injector: the superconducting RFQs ECRIS CRYO-PLANT LEBT SRFQs HEB to ALPI CRYOSTAT QWRs

12 Two superconducting RFQs in a cryostat SRFQ1 SRFQ2 beam line 1.38 m 0.74 m

13 The three issues SLOW HE P DRIFTS of S-RFQs 1. Performance in terms of accelerating 10 W rf power 2. Keep the cavity frequency locked vs slow volume changes (He P drifts) and fast vibrations 3. Alignment < ± 0.2 mm betwween cavity and beam axes (beam transmission) 4. Accelerate the beam (no SRFQs had done it yet) SLOW MECH. TUNERS Q~10 9 FAST VIBRATIONS 0.1 Hz FAST TUNERS (ANL)

14 SRFQ resonators: situation on October 23, 2003 Milestones on SRFQs Each cavity had been tested individually on the cryogenic test stand 1. Q-vs-accelerating field OK 2. Stability versus slow and fast frequency drifts OK Requirement n.3 (alignment within ± 0.2 mm between cavities and beam line) controlled off axis

15 What remained to be done Complete assembly of the RFQs in the final cryostat, deliver it in the accelerator, bring them to 4 K and check alignment (issue n.3) Obtain specified accelerating/focusing 10 W rf power on line (issue n.1) Check frequency locking on-line, where liquid He is fed by the P-drifting and possibly noisy TCF50 refrigerator (issue n.2) Get the beam through (issue n.4) Then, beyond the SRFQs Beam through entire PIAVE, then ALPI, then reliably to the user experimental station

16 (1) (2) (3) 2 PROBLEMS DELAY THE INJECTOR SCHEDULE (1) During assembly: alignment and room-t tests OK, cold leak in an innermost indium vacuum seal (5 wks of intense work for opening everything and fixing). (2) During cold tests (77 K): the mechanical motion of the end plate tuners get stuck significant revision of the design appears mandatory (3) Before fixing (2), we decide NOT to postpone the 2 nd last intervention of Linde Kr on the cryo plant, scheduled then for February 2004

17 (1) (3) (2) (3) 1) Fixing the cold leak during assembly (+5 wks) 2) Developing new mechanical tuners: +3 months 3) Intervention of Linde Kr. on automated filling of cryostats, split into 2 phases (+1.5 months)

18 03-05/2004: full refurbishing of slow mechanical tuners and their tests at 300 K and 77 K

19 05/2004: latest cryostat assembly

20 06/2004: SRFQ cryostat connected to TCF50 refrigerator

21 06/2004 Cryostat assembly and alignment Achieved alignment precision <±0.3 mm (300 & 77 K) 02 and 06/2004: After Connection and cooldown, RFQ alignment is kept within ± 0.2 mm Issue n.3 achieved on line

22 SRFQ1 - SRFQ2: on-line performance (Nov 04) Issue n.1 achieved on line 1.E+09 Q 1.E+08 SRFQ1 SRFQ2 P RF-4K ~6 W P RF-4K ~15 W Field calibration has been checked by detection of Bremsstrahlung: OK < ± 3% 1.E Peak Surface Field [MV/m] Q values are loaded by a factor 2 5 by the presence of the Cu Fast Tuners, However they dissipate power in a liquid-n bath, hence the liquid He consumption is not affected The rf power at charge of the liquid He bath is measured by He gas evaporation

23 On-line stability tests (Nov 04) Phase & Amplitude errors [V] Phase & Amplitude errors [V] SRFQ SRFQ2 Time [arb. Units] Time [arb. Units] A particularly noisy sample is shown (40 min in total) P/ t < 2 mbar/min (Cryo specs) thanks to joint work of Linde Kr. And LNL team The larger fast tuner window of SRFQ2 (200 vs 80 Hz) grants better stability P [mbar] P [mbar] Issue n.2 nearly achieved on line

24 New Injector: the superconducting QWRs ECRIS CRYO-PLANT LEBT SRFQs HEB to ALPI CRYOSTAT QWRs

25 PIAVE: QWR cavities 1.00E+10 PIAVE 80 MHz, β=0.047 QWR PIAVE bulk Nb QWR's Q at 7W Q 1.00E E+08 Needed by first beam tests new specifications old specifications 1.00E Ea (MV/m)

26 New Injector: the cryogenic system ECRIS CRYO-PLANT LEBT SRFQs HEB to ALPI CRYOSTAT QWRs

27 Linde TCF50: liquid He refrigerator Plant completed in summer 2002 Power tests Sep 2002 Results: K with liquid Nitrogen pre-cooling (within specs) Oct 2004: made it possible to fulfill the most stringent spec ( P/ t < 5 mbar/min) October 22, 2003

28 The PIAVE Bunchers ECRIS CRYO-PLANT LEBT 3H-B SRFQs HEB1 to ALPI HEB2 CRYOSTAT QWRs

29 The PIAVE Bunchers 3-harmonic buncher in front of the SRFQs: tested and extensively used during beam commissioning: OK High Energy Bunchers: they rebunch the beam between PIAVE and ALPI. HEB1: tests OK in the foreseen operative conditions kw). HEB2: has been assembled, aligned and equipped (going to be tested)

30 First beam tests through PIAVE SRFQ-Cryostat ECR + LEBT Cryostats for QWR resonators ALPI Dec2004: 1.3 µa, 20MeV di 16 O 3+ (T~40%) Dec2004: 100 na,70 MeV di 132 Xe 18+

31 ALPI ECRIS 2001 then Sep 2004 Bunchers Beam tests in 3 phases Buncher Diagnostics T,L SRFQs ECRIS QWRs Nov 2004 ECRIS Dec 2004 Buncher I x,x y,y E,t SRFQs SRFQs QWRs QWRs Diagnostics T,L QWRs Bunchers Bunchers ALPI ALPI

32 LEBT Commissioning (2001) t < 500 ps Transmission: 89% Diagnostics T,L Proper matching obtained in 2001 Repeated in Spring 2004 (after a fire on the ECR platform)

33 Phase II: setting of RFQs (Nov 04) ALPI ECRIS Free parameters: Free parameters:v B e φ B for the 3 harmonics V 1 e V 2, φ 1 e φ 2 SRFQs QWRs HE Bunchers Buncher Parameters optimized for 12 O 3+. Scaling for 132 Xe 18+. Optimized transport. Measurement of E, ε L with Si det. ( E, Φ). Misura di ε x, ε y. Measurement of transmission. E = 9.3 MeV φ = 730 psec 16 O 3+ E = 75 MeV ε L < 0.5 kev/u*nsec 132 Xe 18+ ε x N RMS = 0.04 mm mrad ε y N RMS = 0.09 mm mrad T = 40 50% (I D /I S ) I D = 70 pna ε xn RMS =0.28 mm mrad ε y N RMS = 0.10 mm mrad T = 25-30% (I D /I S ) I D = 1pnA ( 430 pna OK for SRFQs)

34 Phase III: setting of QWRs (Dec 04) ALPI ECRIS Buncher Free parameters: 8 QWR phases; Constant field in QWRs SRFQ QWR HE Bunchers Diagnostics T,L Setting E a of QWR cavities for 16 O 3+ (63% of 238 U 25+ value). Search of correct phases with Si detector. Measure of E, ε L ( E, Φ). Measure of ε x, ε y. Measure of transmission. Same for 132 Xe 18+ (86% Ea U) E = 20.8 MeV 16 O 3+ ε L < 5 MeV deg ε x N RMS = mm mrad ε y N RMS = 0.4 mm mrad T = 40 50% (I D /I S ) I D =fino a 430 pna First tests (not completed) Beam acceleration after QWR s. Transmission: 25% I D =5.5 pna Si detector degradation stops measurem. session 132 Xe 18+

35 PIAVE: present status 12/2004: 1.3 µa,20mev 16 O 3+ (transmission 40 %) 12/2004: 100 na,70 MeV 132 Xe 18+

36 Phase IV: injetion into ALPI (Mar 05) ECRIS Buncher SRFQ QWR Diagnostics T,L 1. Setting of field and phase of HE Bunchers for best matching with ALPI. Then magnets setting. 2. Further diagnostic stations made available in that branch: 1. (emittance box, FC, Si det. (E, E, Φ)) (temporary) 2. (F.C., Si det. ) 3. (quarz) 4. ALPI diagnostics (FC, hor. grids, MCP, Si det.) 3. By measuring in box n.3 we do not interfere with ALPI operation 1 ALPI HE Bunchers 2 4 3

37 Completion of this part so far impeded by a major fault and a long stop of ALPI cryogenic plant

38 PIAVE: after some hardware work, it was ready to continue beam tests next wk, but the cryo-plant compressor motor seems to require urgent maintenance (to fix it is expected to be technically trivial). Meanwhile work on reliability for the sake of future operation; next beam 03 04/05 ALPI: the low-β branch programme will be completed, immediately after solving the present fault on the cryogenic plant. PIAVE+ALPI beam tests will follow.

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40 Element Charge State Current (ena) Isotopic Abundance ECR-Current (pna) 63 Cu Kr Ag Sn Xe Pr