The ISIS Dual Harmonic Upgrade

1. The ISIS Dual Harmonic Upgrade Andy Seville Joint Accelerator Workshop March 28th, 2006 The Council for the Central Laboratory of the Research Councils

2. Single Harmonic P Error → Voltage → RF Phase → ISIS Dual Harmonic Acceleration Dual Harmonic 50% More Protons! Enlarge Stable Region Optimise trapping Reduce Loss Add 2nd Harmonic RF Component RF Phase →

3. ISIS Dual Harmonic Acceleration The required Accelerating Field is given by V = Vo (sin - .sin (2+ ) ) The voltage on Cavity Gaps is V = -Vo sin () + .Vo sin (2 + ) where Vo and  are +ve.  and chosen to minimise loss during injection, trapping and acceleration cycle

4. ISIS RF Systems - Overview 13kVpkat 12 1RF accelerating gaps +10kVpk at 8 2RF accelerating gaps

5. ISIS Dual Harmonic Acceleration Changing Bias Current changes inductance of ferrite & therefore resonant frequency of the cavity. Every 20ms:-

6. Beam Compensation Loop Phase Loop Cavity Tuning Loop ALC Loop 2RF System Schematic LPRF Controls: Amplitude, Phase & Cavity Tuning Trim Function Bunch Length Loop Anode Power Supply 2nd Harmonic Beam Compensation Loop Frequency Law Summing Amplifier Master Oscillator 1.3 MHz - 3.1 MHz Frequency Doubler 2.6 MHz – 6.2 MHz Frequency Law Generator LPF Sum Electrode Dipole Search Coil Beam Phase Loop Radial Loop Func. Gen. Variable Delay Cavity Bias Regulator Low Voltage Power Supply Existing Fundamental RF System Func. Gen. Variable Gain 1RF 2RF Driver Amplifier To Other 2nd Harmonic Cavity LPRF Systems Func Gen. Summing Amplifier Super-period Phase Splitter Phase Modulator 2  Phase Shifter RF Level Controller LPRF Controls: Amplitude, HPD Cavity 2nd Harmonic Cavity Voltage Loop 2nd Harmonic Cavity Tuning Loop 2nd Harmonic Cavity Phase Loop RF Detector Digital Signal Processor Gated Summing Amplifier Phase Detector (Cavity Tune) 2 RF Limiters A single Burle 4648VI tetrode is used to drive the 2RF cavity Cavity Lock LPF 2 2 Cavity Gap A Voltage Monitor Cavity Lock Servo Phase Networks RF Summing Amplifier Phase Detector (Cavity Lock) Delay Unit Cavity Bias Regulator Func. Gen 2nd Harmonic low power RF 2nd Harmonic high power RF Phase Modulation and Delay Chassis

7. PSU - Splat! + PSU Tripping + ISIS Schedule + Machine Downtime

8. 2RF Commissioning - Preliminary Results • 95% • 93.5% DHRF Acceleration beam intensity and beam loss (2 x 2RF Cavities)

9. Schematic of fundamental frequency and 2nd harmonic RF lock loop Fundamental System Var.  Trim 1 RF. Cav. Phase Mod az±0/ 90 ( = 0/-18/-36) M. O. Cavity Lock Phase Mod Det. 90 A  Ref. Frequency Doubler Var. az±45 Phase Mod Cavity lock Phase Mod Trim 2 RF. Cav.  Phase Mod Det. 90  Ref. 2RF System B Simulated by Cable Delay and Summing Amp

10. ISIS 2RF System Phase Modulation Phase offset for location of each system around ring

11. ISIS 2RF System Phase Modulation 10kV 200V +90° 2RF5 0° 2RF4 -90° 8:1 reduction in combined gap volts (simulated!) (SP4+SP5) / (SP4-SP5)

12. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 0.2ms N - protons Animated Version?

13. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 0.3ms N - protons Animated Version?

14. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 0.4ms N - protons Animated Version?

15. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 0.5ms N - protons Animated Version?

16. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 0.6ms N - protons Animated Version?

17. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 0.7ms N - protons Animated Version?

18. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 0.8ms N - protons Animated Version?

19. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 0.9ms N - protons Animated Version?

20. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 1.0ms N - protons Animated Version?

21. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 1.5ms N - protons Animated Version?

22. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 2.0ms N - protons Animated Version?

23. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 3.0ms N - protons Animated Version?

24. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 4.0ms N - protons Animated Version?

25. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 5.0ms N - protons Animated Version?

26. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 6.0ms N - protons Animated Version?

27. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 7.0ms N - protons Animated Version?

28. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 8.0ms N - protons Animated Version?

29. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 9.0ms N - protons Animated Version?

30. Dual Harmonic Pulses DHRF Acceleration with 3 x 2RF cavities Beam Pulses @ 9.5ms N - protons Animated Version?

31. 2RF SP5 APS Current SP4 ,5 & 6 accelerating Theta Theta Phasing Results APS Current (no beam) 7Apk -72° APS Current (with beam) 5Apk 0° Theta 2RF SP5 APS Current SP4, 5 & 6 accelerating Theta = 0

32. Challenges • Solve Anode PSU tripping problem • Complete cavity phasing tests • DHRF Acceleration with all 4 2RF cavities • Run 2RF Cavities reliably • Increase beam current!