PS 200 MHz RF Matrix and Control Application

2. PS 200 MHz RF Matrix and Control Application as seen from the hardware side H. Damerau Acknowledgments: A. Butterworth, D. Cotte, S. Hancock, C.-H. Sicard 50 AB/OP Shutdown Courses 2009 16 March 2009

3. The new application program • 2nd part by Denis Outline • Introduction • The 200 MHz RF system in the PS • Longitudinal blow-up • Control of the hardware of the 200 MHz system • Concept of re-start timings • Voltage program generation • The new application program • 2nd part by Denis • Summary

4. Please interrupt for questions!

5. 200 MHz RF system • The PS is equipped with six 200 MHz cavities • Originally foreseen for bunch-to-bucket transfer with the SPS, but never operational (~1978, instabilities) • Since 2006 run: number of cavities reduced from 8 to 6 • Therefore now used for - Longitudinal emittance control (a.k.a. blow-up) - 200 MHz rebunching before transfer of fixed target beam (SFTPRO/CNGS) • Cavities: - Short pill-box resonator - Reduced Q with strongly coupled load - 3 PIN diode switches/cavity to reduce residual impedance when not in use • PRF  25 kW/cavity → ~ 25 kV • C202/C203 equipped with fast loudspeaker-tuner

6. 200 MHz RF system PS CB (353): generation of 200 MHz RF signals and voltage programs 6 × Vgap for voltage control North hall (151): amplification to 6 × 25 kW Tunnel (SS06): cavities • ~ 25 Racks of electronics

7. Outline • Introduction • The 200 MHz RF system in the PS • Longitudinal blow-up • Control of the hardware of the 200 MHz system • Concept of re-start timings • Voltage program generation • The new application program • 2nd part by Denis • Summary

8. Beam Cavity Longitudinal blow-up (beam for AD) 1. Low energy blow-up, h = 458 2. High energy blow-up, h = 420 gtr 0.94 eVs 1.3 eVs • 200 MHz system is operated in pulsed mode at various times during the cycle (all high-intensity beams) • Emittance blow-up is achieved by phase modulation

9. fmod = 14 kHz, fmod = 180° (RMS) How does the blow-up work? • Modulate the phase of the 200 MHz voltage to shake the particle distribution • Modulation frequency must be well above synchrotron frequency to avoid resonant excitation AD Injection

10. Modulation parameters Df = 3.141 rad fmod= 1 – 12 kHz VRF= 1 - 30 kV Harmonic number hb = 458, 433, 420 • Low energy: 458th beam harmonic steered to cavity resonance Need to lock the 200 MHz signal to frev • AD cycle with blow-up during first 20 ms after injection • Intensity: ~ 1.35 · 1013 ppp → 3.4 · 1012 ppb Set-up for operational blow-ups with 200 MHz Beam Cavity 199.95 MHz

11. frev V ~ fRF High energy blow-up f Df 1 frev (digital) for h calculation hvar Injection f ~ 200 MHz AD fRF • Harmonic number changes automatically (h = 458 → 419) • The cavities can only be active at a fixed harmonic number! • One RF signal distributed to all six cavities RF signal for the 200 MHz RF system fRF Frequency multiplier fRF = h· frev 199.948 MHz

12. Vgap 199.948 MHz fRF Reflected power • Blow-up during acceleration (e.g. HE blow-up of LHC beams only works in small time windows • Frequency used for blow-up sweeps through cavity resonance High energy blow-up on the fly (LHC) Blow-up cannot be applied anywhere in the cycle! • Need frequency window with constant harmonic number • Need h · frev sufficiently close to 199.948 MHz

13. Outline • Introduction • The 200 MHz RF system in the PS • Longitudinal blow-up • Control of the hardware of the 200 MHz system • Concept of re-start timings • Voltage program generation • The new application program • 2nd part by Denis • Summary

14. Control of the 200 MHz RF system Well known part… • Controls structure has been renovated to run the system without the ancient matrix hardware • How to control the hardware behind?

15. How to control the hardware? • Each cavity needs: • An RF signal at ~ 200 MHz (including the modulation) • Voltage program • Timing signals to release PIN diodes • Timing signals to start and stop the voltage control loop (AVC) • < 2009: 200 MHz matrix in hardware • Built in 1984 • Sophisticated logics inside • Special chassis with custom made cards • Few spare components J. Evans, PS/RF/Note 84-5

16. The old 200 MHz matrix hardware C201 Blow-up 1 … … MATRIX Control System Re-bunching 1 C206 • The control system generates per blow-up/re-bunching: • One voltage function • Three timings: warning, start, stop • The matrix converts these signals to the corresponding timings and voltage programs per cavity • Diagnostics: voltage program and detected per cavity on OASIS

17. Remove matrix C201 … Control System C206 • Control system generates functions and timings directly per cavity • Old hardware matrix not needed anymore • How can a matrix like structure be implemented? • Which control structure reflects hardware structure?

18. New controls structure: Timing trees • Construct a virtual matrix in rows • All the timing information of one row contained in an LKTIM timing tree • Timing trees per blow-up and re-bunching • The LKTIM trees contain start timings for each cavity • The new application program enables/disables timings

19. New structure: Single voltage program • Due to the hardware structure of the 200 MHz system a single RF signal at a time is distributed to all cavities • All cavities always do the same function (blow-up/re-bunching) • Blow-ups or re-bunchings must never overlap • There is no use in sending different voltage programs to different cavities • A single voltage program (GSV200 like GSV10GLOBAL) function for all cavities is adequate Test signal RF signal to all cavities RF from SPS Modulated RF for blow-up

20. Combine: Internal Stops • Combine timing trees and global voltage program function to coherent structure: • Global voltage program with internal stops • Sequence of voltage programs for blow-ups and re-bunchings in time order • Two sections per blow-up/re-bunching: Rising and falling edge of Vprog • Sequence voltage program excludes overlapping • Hardware wired structure (one RF for all) well reflected

21. Closer look on a timing tree • Example: timing tree for blow-up 1 Information of a matrix row stored in timings To be handled by matrix application • New timing tree structure not very different from existing

22. Interlock and diagnostics • Level2 interlock inputs of the old hardware matrix: • Disables all signals to a cavity, if not fully in ON state (level2) • The AVC loop modules are modified with an additional enable • Analogue signals to OASIS are derived from the voltage program per cavity at the output of the old matrix • A voltage program signal per cavity is important for a direct correspondence to the detected voltage • The AVC loop modules are modified with an additional switched voltage program output (simple)  OASIS signals Direct correspondence of program and detected signals remains

23. Outline • Introduction • The 200 MHz RF system in the PS • Longitudinal blow-up • Control of the hardware of the 200 MHz system • Concept of re-start timings • Voltage program generation • The new application program • 2nd part by Denis • Summary

24. New application software 2nd part by Denis

25. • Newcontrol structure close to the structure of the hardware of the 200 MHz system • Direct correspondence of analogue signals Vprog and Vdet • New matrix has been operated at the end of last year’s run Summary • The 200 MHz RF system is essential for all high-intensity beams in the PS • Longitudinal blow-up is achieved by a phase modulated RF signal at a high harmonic (h = 420 – 458) • New control structure replaces ancient hardware: • Timing trees to handle matrix rows of cavity selections • Total voltage function with internal stops for all cavities together

26. Thank you for your attention!