1. CERN LEIR Low Level RF Maria Elena Angoletta AB/RF CERN, Geneva on behalf of the LEIR LLRF team Invited Talk 55 LLRF05: Workshop on Low Level RF CERN, 10-13 October 2005

2. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 2 / 18Outline 1.LEIR & I-LHC, LLRF requirements. 2.LEIR LLRF system: overview, layout & roadmap. 3.PSB beam control test results. 4.Conclusions & acknowledgments.

3. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 3 / 18 LEIR & I-LHC [1]  LHC to collide heavy ions from 2008. Pb 82+ first, lighter ions later. Figure 1: ions for LHC – bold yellow line (Linac3-LEIR- PS-TT2-TT10-SPS-LHC). [1]S. Maury et al.,”Ions for LHC: Beam Physics and Engineering Challenges”, PAC05, Knoxville, USA, May 2005.  Injectors upgrade → Ions for LHC (I-LHC) project.  LEI LEIR EAR  Low Energy Ion Ring (LEIR): key-element, upgraded from Low Energy Antiproton Ring (LEAR).

4. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 4 / 18 Figure 2: Nominal LEIR cycle for Pb 54+. Coasting beamBunched beam Lighter ions after ~2011: In 37+, Kr 29+, Ar 16+, O 8+ LEIR [2] Table 1: LEIR params. for Pb 54+ - nominal cycle. Multiturn injection Electron cooling Acceleration Extraction Pb 54+ intensity (EXT)9 ·10 8 Harmonic number h2 f REV, INJ [kHz]361.3 f REV, EXT [kHz]1423 f S, AFTER_BUNCHING [Hz]600 f S,EXT [Hz]2000 T INJ [MeV/u]4.2 T EXT [MeV/u]72.2 Repetition period[s]3.6 [2]M. Chanel, “LEIR, the Low Energy Ion Ring at CERN”, EPAC02, Paris, France, June 2002. (ion) pulses ~200 μs, low-intensity bunches ~200 ns, high-density Conversion to by accumulation & cooling.

5. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 5 / 18 LLRF requirements  Pulse-to-ulse Modulation sequencing  Pulse-to-Pulse Modulation sequencing  Nominal operation: h = 2  Early operation: h = 1 → f RF, MIN = 0.36 MHz.  Wide f REV range  f RF in [0.7 – 2.8 MHz] for Pb 54+.  f RF in [0.7 – 5 MHz] for lighter ions. magnetic alloy-based (Finemet®), wide-band, non-tunable cavity [3]. [3]M Paoluzzi, “The LEIR RF System”, PAC05, Knoxville, USA, May 2005. Figure 3: LEIR cycle is composed of several users during commissioning. Figure 4: LEIR cavity impedance Z  High cavity Z for cooled beam  Cavity servoloop tuned on h & 2h.  Real-time control of gap relay to short-circuit cavity.  High cavity voltage dynamic range  High cavity voltage dynamic range (~60 dB)  Dual harmonic operation on a single cavity  Dual harmonic operation on a single cavity (h, 2h)

6. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 6 / 18Outline 1.LEIR & I-LHC, LLRF requirements. 2.LEIR LLRF system: overview, layout & roadmap. 3.PSB beam control test results. 4.Conclusions & acknowledgments.

7. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 7 / 18  Started fall 2003 as CERN-BNL collaboration (now mainly CERN effort). →  All-digital beam control & cavity servoloop: a first @CERN! → new skills required. →  Addresses all RF requirements ( → slide 5 ). LEIR LLRF [4] overview [4] LEIR LLRF website http://project-leir-dsp-bc.web.cern.ch/project-leir-dsp-bc/ Beam control capabilities  frequency program,  radial + phase + synchro loops,  I/Q servo-loop for cavity voltage phase/amplitude,  radial steering, frequency offset …  beam phase ~ 20 kHz,  cavity servo ~ 20 kHz,  radial ~ 1 kHz. Expected loops BW  Modular design (h/w + s/w).

8. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 8 / 18 Hardware DDCSDDSMDDS Hardware: DSP-carrier board + daughtercards (DDC, SDDS, MDDS). Other modules (rear transition, clock fanout …) not listed here. LEIR LLRF overview – cont’d  DSP-carrier  DSP-carrier:  Function: beam ctrl, carries daughtercards, s/w int’face, diagnostics...  6U VME64x, ADSP21160M DSP, 8 MB memory, FPGAs (glue-logic & light processing).  Inter-DSP data exchange via linkports™.  Master Direct Digital Synthesiser  Master Direct Digital Synthesiser: [5]  Function: tagged clock [5] (single/double) generation.  AD9858 1 GHz DDS + Stratix. LVDS + Firewire connector & cables. Figure 6: Tagged clock – schematic view. [5] R. Garoby, “Multi-Harmonic RF Source for the Anti-Proton Production Beam of the AD”, PS/RF/Note 97-10. Figure 5: MDDS daughtercard – schematic view.

9. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 9 / 18 LEIR LLRF overview – cont’d Figure 7: DDC daughtercard – schematic view.  Function: tunable RF receiver. CIC filter under DSP control.  ADC (AD9245, 14 bits, 80 MHz) + Stratix. SRAM (256 k x 16 bits).  Diagnostics info to DSP.  Digital Down Converter (4 channels)  Digital Down Converter (4 channels):  Digital I/O for cavity interfacing.  Slave Direct Digital Synthesiser(4 channels)  Slave Direct Digital Synthesiser (4 channels):  Function: analogue voltages generation (cavity voltages + RF trains).  DAC (AD9754, 14 bits, 125 MHz) + Stratix. SRAM (256 k x 16 bits).  Switched DAC I ref for high output dynamic range. Figure 8: SDDS daughtercard – schematic view.

10. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 10 / 18 LEIR LLRF overview – cont’d  Data retrieval for system diagnostics & monitoring. Aim: system fully configurable/monitored from control room.  Reference function & timing events generation. Software DSPsFPGAs Software : floating point DSPs + FPGAs.  Use of DSP SIMD capabilities (ex: phase rotation)  H/w blocks mapped to s/w blocks (from DSP to application). RF-specific application program  Synoptic for easy understanding.  MATLAB available for offline data analysis. Figure 9: RF-specific application. Radial loop window. Complex (I & Q) data FPGA processing 4 radial loop corrector setups Reference function

11. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 11 / 18Layout Figure 10: LEIR LLRF schematic view. DSP A Frequency program, radial loop & RF trains gen. DSP B Phase & synchro loops DSP C Vector sum calculation & cavity servoing B up B down Tagged clock TPU 1 & 2 1 & 2RFtrains PhasePURFref Cavity 1 & 2, h RF & 2h RF Digital I/O Gap relay ctrl, beam status Linkport40 MHz ref Middleware MATLAB

12. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 12 / 18Roadmap Export technology to CPS accelerators (PSB, AD, PS). Advantages: standardisation & easier maintenance. System important “per se” & as pilot project. Digital beam control system suited for low-frequency synchrotrons with high frequency swing Digital beam control system suited for low-frequency synchrotrons with high frequency swing.  LEIR acceleration + digital LLRF commissioning Feb ’06.  PSB testing system prototype beam control test results. (the beam never lies…)

13. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 13 / 18Outline 1.LEIR & I-LHC, LLRF requirements. 2.LEIR LLRF system: overview, layout & roadmap. 3.PSB beam control test results. 4.Conclusions & acknowledgments.

14. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 14 / 18 Capture & acceleration efficiency Results Table 3: Efficiency results PSB test results  Scaled-down prototype system tested in PSB (2004 [6] & 2005).  PSB: f REV & f S range similar to LEIR. [6]M. E. Angoletta et al., “Beam Tests of a New Digital Beam Control System for the CERN LEIR Accelerator”, PAC05, Knoxville, USA, May 2005. 10 11 p% Injection7.66 Capture7.3696.1 Acceleration7.3599.9 ParameterUnitLEIRPSB INJ. f REV MHz0.3610.599 fSfS kHz0.6002.000 TMeV/u4.249.62 EXT. f REV MHz1.4231.746 fSfS kHz2.0000.470 TMeV/u72.21374.2 Cycle times3.61.2 Accel. times~10.5 Table 2: LEIR and PSB parameters comparison.

15. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 15 / 18 PSB test results – cont’d  rad. steering: 468 & 612 ms.  set rise time T r ~ 2ms.  optimised PI: 468 & 612 ms. Figure 11: Phase loop response to step, zoomed onto fast & slow step response. Result Result: slow & fast time constants as expected. Phase loop dynamics Radial loop dynamics Figure 12: Radial loop response to radial steering. Test  set f PL = 7 kHz, 570 Hz.  add 0.2 rad (step) to φm.  observe φ m. Test Result Result: measured T r as expected.

16. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 16 / 18Outline 1.LEIR & I-LHC, LLRF requirements. 2.LEIR LLRF system: overview, layout & roadmap. 3.PSB beam control test results. 4.Conclusions & acknowledgments.

17. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 17 / 18Conclusions  LEIR LLRF: digital system suited for low-frequency machines with high frequency swing.  A first @CERN – change of culture + new skills.  Soon to be commissioned in LEIR.  Beam control capabilities tested in PSB with good results.  Fully configurable/monitored from control room.  DSPing/control by DSPs + FPGAs.  Long-term plan: export technology to CPS accelerators. Aim: standardisation & maintainability.

18. M.E. Angoletta - LLRF05 workshop CERN LEIR Low Level RF 18 / 18Acknowledgments Joe DeLong Many thanks to Joe DeLong (BNL) for initial board development current CERN LEIR LLRF team & to the current CERN LEIR LLRF team:  J. C. Allica Santa Maria (technical student),  M. E. Angoletta (project leader),  J. Bento,  A. Blas,  E. Bracke,  A. Butterworth,  A. Findlay,  P. Matuszkiewicz (fellow),  F. Pedersen,  T. Rohlev.