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

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

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

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

ISIS Dual Harmonic Acceleration Changing Bias Current changes inductance of ferrite & therefore resonant frequency of the cavity. Injection Extraction Proton Energy 70MeV 800MeV Rotation Freq 0.65 MHz 1.55MHz 1RF Freq 1.3 MHz 3.1 MHz 2RF Freq 2.6 MHz 6.3 MHz Bias current 200 A 2000 A Every 20ms:-

2RF System Schematic Phase Loop Beam Compensation Loop Cavity Tuning Loop ALC Loop LPRF Controls: Amplitude, Phase & Cavity Tuning Trim Function Bunch Length Loop 2nd Harmonic Beam Compensation Loop Anode Power Supply Frequency Law Generator Frequency Law Summing Amplifier Master Oscillator 1.3 MHz - 3.1 MHz Frequency Doubler 2.6 MHz – 6.2 MHz 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 Shifter 2 Phase Modulator LPRF Controls: Amplitude, RF Level Controller 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 Cavity Lock LPF RF Limiters A single Burle 4648VI tetrode is used to drive the 2RF cavity 2 2 Cavity Lock Servo Cavity Gap A Voltage Monitor Phase Detector (Cavity Lock) Phase Networks RF Summing Amplifier Delay Unit Cavity Bias Regulator Func. Gen 2nd Harmonic low power RF 2nd Harmonic high power RF Phase Modulation and Delay Chassis

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

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

Schematic of fundamental frequency and 2nd harmonic RF lock loop Fundamental System Var. M. O. Phase Mod az ±0/ 90 ( = 0/-18/-36) Cavity Lock Phase Mod  Trim 1 RF. Cav.  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

ISIS 2RF System Phase Modulation Phase offset for location of each system around ring  2RF4 2RF5 2RF6 2RF8 Az Shift 21.5 73.55 109.5 165.5 1RF Phase 43 147.1 219 331 2RF Phase 86 294.2 438 662

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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