Operational Experience with J-PARC Injection and Extraction Systems

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1 Operational Experience with J-PARC Injection and Extraction Systems Pranab Kumar Saha Japan Proton Accelerator Research Complex (J-PARC) 46th ICFA Advanced Beam Dynamics Workshop ( HB2010 ) Morschach, Switzerland. ( 27 Sept. 1 Oct ) P.K. Saha HB2010 1

J-PARC (JAEA & KEK) Neutrino Beam Line to Kamioka Linac 181 MeV at present, 400 MeV with ACS [600 MeV SCL in phase2 for TEF] 3 GeV Rapid Cycling Synchrotron (RCS) 50

2 J-PARC (JAEA & KEK) Neutrino Beam Line to Kamioka Linac 181 MeV at present, 400 MeV with ACS [600 MeV SCL in phase2 for TEF] 3 GeV Rapid Cycling Synchrotron (RCS) 50 GeV Main Ring Synchrotron (MR) [30 GeV in 1 st phase] Materials & Life Science Facility (MLF) JFY 2006 / 2007 JFY 2008 JFY 2009 Hadron Experimental Hall P.K. Saha HB2010 2

3 J-PARC (JAEA & KEK) RCS Inj. Neutrino Beam Line to Kamioka Materials & Life Science Facility (MLF) JFY 2006 / 2007 JFY 2008 JFY 2009 Hadron Experimental Hall P.K. Saha HB2010 3

4 J-PARC today In operation P.K. Saha HB2010 4

5 Introduction and Outline J-PARC (Japan Proton Accelerator Research Complex) is a MW-class accelerator complex for multi-purpose research covering the Material and Life Science, Nuclear and Particle Physics and Nuclear Engineering as well. The entire facility already entered into an operational mode for users. Outline: 1. RCS injection and extraction systems. Recent Achievements and Issues. 2. MR injection and Extraction systems. Recent Achievements and Issues. P.K. Saha HB2010 5

B(T) 3-GeV RCS Design parameters Circumference 348.

per pulse Output beam power 181 MeV (400 MeV with ACS) 3 GeV 25 Hz 2.5e13-5e13 (8.3e13 with 1 MW) 0.3-0.

6 B(T) 3-GeV RCS Design parameters Circumference m Superperiodicity 3 Harmonic number 2 No of bunch 2 Injection energy Extraction energy Repetition rate Particles per pulse Output beam power 181 MeV (400 MeV with ACS) 3 GeV 25 Hz 2.5e13-5e13 (8.3e13 with 1 MW) MW (1 MW with upgraded Linac) Operation mode Transition gamma 9.14 GeV Number of dipoles 24 quadrupoles sextupoles 60 (7 families) 18 (3 families) steerings 52 RF cavities 12 (11 at present) Time(msee) 6

7 3-GeV RCS H0 Dump (4kW) RCS Injection area 2 nd Foil 1 st Foil 3 rd Foil HSTM VSTM DUMP-Q DSEP2 DSEP1 PBH4 PBH3 QFM H injection beam ISEP1 PBV1 PBV2 ISEP2 PBH2 PBH1 SB1 QFL SB2 SB3 SB4 QDL 7

8 Recent achievements and Issues with RCS injection Recent achievements: Transverse painting injection: Realistic painting injection with good accuracy in both H&V planes are being performed. Keep controlling uncontrolled beam loss at the injection for a stable and high power operation. Foil issue concerning life time: Not yet any real problem! A single foil is using for nearly a year which includes several user runs with a beam power of 120 kw! Waste beam monitoring at the H0 (injection) dump Able to monitoring even a lower (0.4%) waste beam (0.4% of the present inj. beam (7.2kW) 30W ) at the H0 dump. Direct monitoring of the foil life time. P.K. Saha HB2010 8

Recent achievements and Issues with RCS injection Waste beam

6% Waste beam ~ 0.4% H0CT raw signal FFT Peak value @ RF Frequency (0.

2kW 120kW@3GeV Off-line analysis Peak:15mA, Macro:500 s, Duty:560ns,

9 Recent achievements and Issues with RCS injection Waste beam monitoring at the H0 (injection) dump Stripping efficiency ~ 99.6% Waste beam ~ 0.4% H0CT raw signal FFT Peak RF Frequency (0.94 MHz) Inj beam: 7.2kW 120kW@3GeV Off-line analysis Peak:15mA, Macro:500 s, Duty:560ns, 2b 18kW eqiv. (Full inj. beam) FFT RF Fundamental Freq. 940kHz Linear scale (0.38±0.05)% Good S/N ratio Raw signal P.K. Saha HB2010 9

10 Recent achievements and Issues with RCS injection Recent achievements: Transverse painting injection: Realistic painting injection with good accuracy in both H&V planes are being performed. Keep controlling uncontrolled beam loss at the injection for a stable and high power operation. Foil issue concerning life time: Not yet any real problem! A single foil is using for nearly a year which includes several user runs with a beam power of 120 kw! Waste beam monitoring at the H0 (injection) dump Able to monitoring even a lower (0.4%) waste beam (0.4% of the present inj. beam (7.2kW) 30W ) at the H0 dump. Direct monitoring of the foil life time. P.K. Saha HB

11 RCS injection: Recent issues Foil Scattering loss: -- Two uncontrolled hot points near the RCS injection area (1) H0 dump branch, (2) Near QFM (BPM2-1) (mostly at the ring side and only in the horizontal direction) Caused by the large angle multiple Coulomb scattering at the foil! P.K. Saha HB

12 Ring Collimator Foil scattering loss H0-Septum2 H0-Q QFM H0-Septum1 QDL PBH3 PBH4 QFL SB1 SB2 SB3 1 st Foil SB4 Typical residual radiation 120 kw user operation ~ 5 hours after beam shutdown 1200~1700 on contact ( 60~ cm apart ) P.K. Saha HB

at the H0 branch and BPM locations are identified.

13 y(mm) x(mm) Acceptance simulation Courtesy: H. Harada Horizontal -30mrad +30mrad Geant + SAD w/ 10 8 macro particles Two hot points only in the horizontal direction at the H0 branch and BPM locations are identified. FOIL Vertical QDL H0 PBH3 PBH4 branch BPM QFM x QFL ISEP1,2 1 st Foil QDL Shift bump orbit Painting 100 Painting 200 S PBH1,2 SB1 SB2 SB3 SB4 PBH3,4 Orbit moves towards outer side w/ larger painting area Loss reduced in the inner side! P.K. Saha HB

14 rate rate Comparison of beam loss between simulation and experiment ( Geant + SAD ) ( Integrated BLM signal ) (1) H0 branch (ring side) (2) Near QFM (ring side) 1/3m ode(sim ulation) 1/3m ode(m easurem ent) 1/3m ode(sim ulation) 1/3m ode(m easurem ent) DCm ode(sim ulation) DCm ode(m easurem ent) DCm ode(sim ulation) Dcm ode(m easurem ent) Consistent! Consistent! /3 mode: foil hit = DC mode w/ paint 150 : foil hit =9 BLM 0.4 gain was different 0.2 Bigger painting area Lower foil hit for 1/30.2 and DC mode Painting area paint ( mm mrad) Painting area paint( mm mrad) P.K. Saha HB

Solutions 1. Optimized foil size reduce foil hit rate ~ 1/2 Current foil size : 110(H)x40(V) Linac beam : ~7 x 7 mm 2 y: 10 mm 40 mm Already installed Check next run!

15 Solutions 1. Optimized foil size reduce foil hit rate ~ 1/2 Current foil size : 110(H)x40(V) Linac beam : ~7 x 7 mm 2 y: 10 mm 40 mm Already installed Check next run!! New foil size 110(H)x15(V) mm 2 x:7 mm Not sufficient!! Residual radiation with 300 kw operation might left about 1.5 msv/h! 2. Local shield Collimator is in consideration! Simulation shows that can localize the beam losses. To be installed in 2011 maintenance period! P.K. Saha HB

16 inner outer Example of localization Courtesy: H. Harada w/ collimator Collimator FOIL QDL H0 branch PBH3.4 BPM2-1 QFM P.K. Saha HB

17 RCS Extraction Kicker Magnets(1~8) Beam transport lines to MLF to MR RCS Septum Magnets(1~3) P.K. Saha HB

18 Progress (1) RCS Extraction: Recent progress and Issues 120 kw user operation for MLF and a max of 300 kw equivalent beam to the MR without any noticeable beam loss at the extraction region kw kw 20 kw Run#20 ~ Run#26 Run#27 ~ Run#34 P.K. Saha HB

Progress (1) RCS Extraction: Recent progress and Issues 120 kw user operation for MLF and a max of 300 kw equivalent beam to the MR without any noticeable beam loss at the extraction region.

19 Progress (1) RCS Extraction: Recent progress and Issues 120 kw user operation for MLF and a max of 300 kw equivalent beam to the MR without any noticeable beam loss at the extraction region. Progress (2) Extraction with 7 kickers (instead of 8 in normal operation) made possible 3500 without any problem 250 Can 3000 reduce the downtime for Kicker 120 kw thyratron exchange (3~4 hrs) Progress 2500 (3) Proper conditioning 2000 and ranging method and setting a suitable rise time for thyratrons 1500 of the kicker magnets. 100 Greatly 1000 increased the life time of thyratron Auto feedback 500 of the kicker 20 kw drift and monitoring thyratron life 50 time. Stabilize extraction 4 kw 0 orbit ( 1 st and 2 nd bunch) 0 Reduce unscheduled downtime for thyratron exchange. Run#20 ~ Run#26 Run#27 ~ Run#34 Altogether makes it possible for almost a negligible downtime related to RCS kicker failure!! P.K. Saha HB

20 Issues RCS Extraction: Recent progress and Issues No other serious issue except leakage field from the extraction DC septa and one bending magnet in the 3NBT line. Extra Shielding done but reduced only ~ 40% cause ~9 mm of COD done correction by steering magnets but in addition to the K0 component it includes also K1 and Skew-K1 components! Destroy Ring Superperiodicity, Excite non structure resonances, etc. Detail: H. Hotchi et. al. PRST-AB 12, (2009) no space for further shielding! Correction by 2~3 additional small quadrupoles are in consideration! P.K. Saha HB

21 Main Ring (MR): Injection and Extractions Bunch configuration in the MR Beam abort line Fast extraction FX Rf cavities Hadron Experimental Hall RCS BT collimators 3-50 BT Injection Ring collimators Neutrino beamline Circumference : m Repetition Rate: ~0.3 Hz Inj. Energy : 3 GeV Ext. Energy : 30 GeV No of Bunches : 8 (6 in day1) Hadron beamline Slow extraction SX Injection Septa MR Injection system MWPM Injection Kickers To Super-Kamiokande Dump Kickers 3 GeV beam dump (3kW) 3-50BT Collimators Bump magnets Dump Septa FWPM P.K. Saha HB

Main Ring (MR): Injection and Extractions Bunch configuration in the MR Beam abort line Fast extraction FX Rf cavities Hadron Experimental Hall RCS Neutrino beamline MR Fast Extraction (FX) system

22 Main Ring (MR): Injection and Extractions Bunch configuration in the MR Beam abort line Fast extraction FX Rf cavities Hadron Experimental Hall RCS Neutrino beamline MR Fast Extraction (FX) system Kicker magnets ( Total: 5 ) Septum magnets ( Total: 8 ) BT collimators 3-50 BT Injection Ring collimators Circumference : m Repetition Rate: ~0.3 Hz Inj. Energy : 3 GeV Ext. Energy : 30 GeV No of Bunches : 8 (6 in day1) To Super-Kamiokande Hadron beamline Slow extraction SX P.K. Saha HB

5 m Repetition Rate: ~0.3 Hz Inj. Energy : 3 GeV Ext.

23 Main Ring (MR): Injection and Extractions Bunch configuration in the MR Beam abort line Fast extraction FX Rf cavities Hadron Experimental Hall RCS Neutrino beamline Unstable region BT collimators 3-50 BT Injection Ring collimators Circumference : m Repetition Rate: ~0.3 Hz Inj. Energy : 3 GeV Ext. Energy : 30 GeV No of Bunches : 8 (6 in day1) Hadron beamline Slow extraction SX Stable region By exciting 3 rd order resonance To Super-Kamiokande MR Slow Extraction (SX) System P.K. Saha HB ESS (1~2) MS (1~3)

24 Intensity (x10 13 ppp) Loss count MR Injection and Extraction: Achievements A total of 6 bunches injection already been able to perform keeping the beam loss in limit. Typical injection loss: 100~200W < 450W collimator limit Injection Collimators SX 1.6 km BLM# FX Courtesy: T. Koseki 100 kw (7.5 e13 ppp!) FX for the NU user operation. (although done only for 3 min) A maximum of 2.6 KW SX for early commissioning of the HD experiment facility. (Although duty factor still very low: ~11% ) FX 100 KW Operation! DCCT Time (ms) DCCT SX 1.9 kw operation P.K. Saha HB

25 Injection MR Injection and Extraction Issues Leakage field from the injection septum II magnet Done extra shielding this summer hope to reduced ~10% Fast Extraction Slower rise time: 1.6 s < required for 8 bunch operation (<1.1 s) Heating problem in the ferrite core limits the NU operation to ~50KW Replacement just done. A faster rise time (<1 s) expectable and also hopefully no more heating problem up to 750 kw! 8 bunches operation would become available Slow Extraction system Low duty factor of only ~11% Several studies including ripple reduction in the ring magnets power supply, ripple reduction using RF noise, new algorithm for the spill feedback system are in progress. P.K. Saha HB

26 Summary Overall operational experience with J-PARC injection and extraction systems are satisfactory, although there remains several issues especially, for further higher power and log term operation. Foil scattering loss is one of the main issues at the RCS injection. Leakage field effect from the RCS DC extraction magnets is also one big issue to concern. New kicker system for the FX and improvement of SX duty factor are two main issues in the MR. Most of the issues are fairly understood and many measures have already been taken in this summer maintenance period. P.K. Saha HB

27 Questions and Answers General questions: 1. What is the most significant design challenge for this system? Ans: Stripping foil. Long survival at high temperature (>1800K). In general, time-consuming process rather than to say challenging in designing the injection and extraction systems and was the compromise of the following items: i) Aperture requirement along possible beam trajectories. ii) Field strength of septum magnets against saturations. iii) Shielding space for the leakage from the septum magnets. 2. Are the calculation/simulation tools available in the field adequate for this problem? Ans: Mostly adequate 3. Is the knowledge base in the field sufficient? Ans: In general yes but experimental studies especially, with high power are necessary. A couple of more questions: 1. Does the system perform as expected? Yes 2. Did the simulations/calculations performed during the design stage accurately predict the actual performance? Ans: Almost yes. P.K. Saha HB

28 Extra slides P.K. Saha HB

Beam Position (mm) RCS injection issues cont d What cause this? IGBT switching freq. 6kHz 8 multiple assemblies makes 48kHz ripple Effect: Resonance at 6.2 =48*2/470=0.

Current control accuracy would be better Suppression by LPF Ripple of Shift bump Revolution freq.@181mev Affects RCS operating tune! Side band at 0.2 Revolution freq.

29 Beam Position (mm) RCS injection issues cont d What cause this? IGBT switching freq. 6kHz 8 multiple assemblies makes 48kHz ripple Effect: Resonance at 6.2 =48*2/470=0.204 How to cure? Prospect for 400MeV =96/614=0.156 Expecting smaller ripple amplitude Because, IGBT assemblies are doubled. Current control accuracy would be better Suppression by LPF Ripple of Shift bump Revolution freq.@181mev Affects RCS operating tune! Side band at 0.2 Revolution freq.@400mev Need to be compromised with falling time Cooling for LPF elements are necessary DC storage mode Stationary RF bucket~1sec SB 25Hz operation BPM turn-by-turn data SB off Time SB on P.K. Saha HB Frequency

Delay(ns) T(ns) RCS Kickers auto feedback result Kicker waveform KM2 KM6 Threshold Two thyratrons for each kickers Reference CH1 Measure CH1 Reference CH2 Measure CH2

30 Delay(ns) T(ns) RCS Kickers auto feedback result Kicker waveform KM2 KM6 Threshold Two thyratrons for each kickers Reference CH1 Measure CH1 Reference CH2 Measure CH2 Monitor T from the reference Kicker#8 Log Thyratron1 Thyratron2 ±30ns Thyratron1 Thyratron2 450ns Time ( s) Time ( s) Unstable Thyratron Exchanged P.K. Saha HB

31 Delay(ns) T(ns) Kicker#8 after thyratron 2 exchange Kicker down ±30ns No drift at all! P.K. Saha HB

Vertical steering magnets (IVSTM1-2) H from linac Vertical paint-bump magnets (PBV1-2) QDN BM QFN Pulsed Steering Magnet (PSTR1,2) ( @ 400 MeV injection ) Horizontal steering magnets (IHSTM1-2) BM

32 Vertical steering magnets (IVSTM1-2) H from linac Vertical paint-bump magnets (PBV1-2) QDN BM QFN Pulsed Steering Magnet (PSTR1,2) 400 MeV injection ) Horizontal steering magnets (IHSTM1-2) BM QDX Injection septa (ISEP1-2) Horizontal paint-bump magnets (PBH1-2) QFL L3BT upstream (exclude steering) Vertical Paint Bump 1,2 (PBV1,2) Pulsed Steering 1,2 (PSTR1,2) Injection Septum 1,2 (ISEP1,2) H0 Dump line Dump Septum1,2 (DSEP1,2) Dump Quad Dump Steering (1V, 1H) RCS Injection System Dump-line septa (DSEP1-2) 2nd MWPM4 foil K-BPM MWPM3 MWPM5 3rd MWPM2 foil I-BPM P.K. Saha HB st foil Shift-bump magnets (SB1-4) QDL Vertical and horizontal steering magnets (DVSTM and DHSTM) Quadrupole magnet MWPM6 QFM Horizontal paint-bump magnets (PBH3-4) Ring Circulation orbit side MWPM7 Injection beam dump (4 kw) Collimator RCS adopted H - charge-exchange injection scheme. Horizontal Paint Bump 1~4 (PBH1~4) Shift bump 1~4 (SB1~4) QFL, QDL

33 How works the whole system J-PARC timing chart P.K. Saha HB

PULSE-TO-PULSE TRANSVERSE BEAM EMITTANCE CONTROLLING FOR MLF AND MR IN THE 3-GeV RCS OF J-PARC

THO3AB3 Proceedings of HB, East-Lansing, MI, USA PULSE-TO-PULSE TRANSVERSE BEAM EMITTANCE CONTROLLING FOR MLF AND MR IN THE 3-GeV RCS OF J-PARC P.K. Saha, H. Harada, H. Hotchi and T. Takayanagi J-PARC