1. LLRF Activities at KEK/J-PARC Zhigao Fang 1 SuperKEKB 2 cERL (compact Energy Recovery Linac) 3 STF (Superconducting RF Test Facility) 4 J-PARC LLRF workshop 2015 @ 2015/11/3 9:14-9:26 1

2. Commissioning will start in February 2016 ! 1 SuperKEKB Luminosity : KEKB x 40 !  Luminosity increases 40 times by 1) beam currents (LER: e+/HER: e-): 1.7/1.4 A → 3.6/2.6 A (2 times) 2)  y at IP (Interaction Point): 5.9 mm → 0.3 mm (20 times) Vertical beam size is reduced to 0.048/0.062 mm (Nano-beam).  RF stations will increase, and higher accuracy and flexibility are required in RF control.  Digital LLRF system is developed to replace the previous analog one. 2

3. New LLRF System for SuperKEKB Previous KEKB analog LLRF system  Good performance was demonstrated in the high power test with ARES cavity.  FB control and auto tuning control worked successfully.  Regulation stability was 0.02% in amplitude and 0.02 deg. in phase. Block Diagram of FB & Tuner Control 3 μTCA crate Mitsubishi Electric TOKKI System Corp. uTCA-platformed FPGA Boards (AMC Card) 16-bit ADC x 4ch, 16-bit DAC x 2ch EPICS-IOC embedded Consisting of μTCA-platformed FPGA boards, PLC, and EPICS-IOC with Linux-OS embedded. New Digital LLRF system

4. ©Rey.Hori/KEK Circumference ~ 90m Marger Beam Dump Compact ERL (cERL) has been constructed as a test facility of a 3-GeV ERL future plan. Main LINAC 9-cell SC cavity x 2 Q L = 1  10 7 Injector LINAC 2-cell SC cavity x 3 (double feed) Q L = 5  10 5 Commissioning has been started from 2013. Nominal beam energy35 MeV Nominal Injector energy5 MeV Beam current10 mA (initial goal) 100 mA (final goal) Normalized emittance < 1 mm  mrad RF frequency1.3 GHz MTCA Digital FB boards Field FB Control Tuner Control 2 cERL 4

5. stabilitiesInj1Inj2 & Inj3ML1ML2 Amp.0.006%0.007%0.003% Phase 0.009  0.025  0.010  0.009  Requirements of RF stabilities: 0.1%rms, 0.1deg.rms for cERL 0.01%rms, 0.01deg.rms for 3GeV-ERL Disturbances: Beam-loading (Burst mode operation) Amp. Phase Inj. 1 ~1.6 ms ~ 800 µA Beam profile PI PI+DOB Introduction of adaptive DOB (Disturbance observer-based) Controller 11/514:20Disturbance observer-based control in LLRF system at cERL F. Qiu 11/49:20Performance of the cERL llrf systemT. Miura cERL LLRF Performance 5

6. STF-2: Prototype of ILC-TDR One 10-MW MBK drives 12 SC cavities. KEK Superconducting RF Test Facility (STF) In STF-2, two digital LLRF boards connected with optical communication are configured for operation. → minimal combination of ILC LLRF system. RF operation will start at May 2016. Beam operation is planned from the autumn of 2016. Optical communication among two boards has been evaluated at test stand. MTCA.4 standard board 14ch ADCs (AD9650, 16bit) 2ch DACs (AD9783, 16bit) Spartan6(XC6SLX) Zynq-7000(XC7Z045): ARM (Cortex-A9) → EPICS-IOC RJ-45 connector, 2ch SFP connectors 3 STF 6

7. Cavity Conditioning at STF (October-December, 2015) Three FPGA boards are operated in MTCA shelf. One is for feedback operation and the others are for monitoring with different algorithm (IF mixture and Direct sampling). ← IF mixture method: Vt, Vf, Vr signals are measured with one ADC. Direct sampling: → Vt, Vr signals are measured without down-converter. Feedback operation Parameters will be adjusted to attain good stability. 7

8. Linac (normal conducting) (pps: 25Hz, 500us, 181  400 MeV, 30  50 mA) Rapid Cycle Synchrotron (RCS) (3GeV, 25Hz, 1MW) Main Ring Synchrotron (MR) (30GeV, 0.75MW) 4 J-PARC 8

9. Improvements on J-PARC LINAC LLRF: Reference timing, Digital feedback, Beam compensation, Auto-tuning systems. Excellent performances ： Very good RF field stabilities are achieved: Without beam324MHz RF Cavities972MHz RF Cavities  A (p-p) / A ～  0.12%  (p-p) ～  0.08  ～  0.11  16 ～ 50mA chopped-beam324MHz RF Cavities972MHz RF Cavities  A (p-p) / A  0.12% ～  0.69%  0.27% ～  0.94%  (p-p)  0.09  ～  0.22  0.16  ～  0.30  J-PARC LINAC LLRF Performances  J-PARC LINAC 11/59:05Overview of J-PARC LINAC LLRF Z. Fang 9

10. New Chopper Controller  J-PARC LINAC 11/415:00Improvement of chopping system at the J-PARC LinacK. Futatsukawa 10 A chopper controller with the capability of 180  phase rotation has been developed. Phase accuracy: 0.34 deg. Amplitude accuracy: 0.5% Intermediate-pulse : 25 ～ ns normal phaserotated phase Comb-like RF with normal and rotated phases The beam current increases ⇒ The heat load for scraper increases. It will be installed at the end of this year. A pair of scrapers

11. High Beam Power Operation & Beam Loading Compensation RCS: 1MW (design value, single shot), 500kW (user operation) achieved in 2015, with small beam loss less than 0.5%. MR: 360kW for neutrino experiment in 2015. For these achievements, digital LLRF control systems served well.  J-PARC Synchrotrons without feedforwardwith feedforward Example: mountain plot during MR injection period oscillation much reduced beam loading induce longitudinal oscillation Beam loading compensation by multi-harmonic rf feedforward is indispensable. Feedforward is open loop: if beam conditions (intensity, longitudinal distribution) are different, the gain and phase of the feedforward may not be optimum. Additional narrow band vector voltage feedback is now considered. 11/415:00Development of narrow band FB for J-PARC synchrotronsF. TAMURA 11

12. Please enjoy them! 4 talks : 2 posters : Presentations from KEK/J-PARC 11/49:20Performance of the cERL llrf systemT. Miura 11/59:05Overview of J-PARC LINAC LLRF Z. Fang 11/510:05Possible LLRF Configuration for ILCS. B. Wibowo 11/514:20Disturbance observer-based control in LLRF system at cERL F. Qiu 11/415:00Improvement of chopping system at the J-PARC LinacK. Futatsukawa 11/415:00 Development of narrow band feedback for J-PARC synchrotrons F. TAMURA 12

13. Thank you very much for your attention ! 13