The ISIS Dual Harmonic Upgrade The Council for the Central Laboratory of the Research Councils Andy Seville Joint Accelerator Workshop March 28th, 2006
Jan 14, 2016
The ISIS Dual Harmonic Upgrade
The Council for the Central Laboratory of the Research Councils
Andy Seville
Joint Accelerator Workshop March 28th, 2006
Add 2nd HarmonicRF Component
RF Phase →
Dual Harmonic
P E
rro
r →
RF Phase →
Single Harmonic
Vo
ltag
e →
Enlarge Stable RegionOptimise trapping
Reduce Loss
ISIS Dual Harmonic Acceleration
50% More Protons!
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.
-2 0 2 4 6 8 10-80
-60
-40
-20
0
20
40
60
Time (ms)
(De
g) theta
phis
-2 0 2 4 6 8 100
50
100
150
200
Time (ms)
RF
Vo
lts (
kV)
1RF volts
2RF volts
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.
Every 20ms:-
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
2RF System Schematic
LPRF Controls: Amplitude,
LPRF Controls: Amplitude,Phase & Cavity Tuning
Driver Amplifier
Anode Power Supply
2nd Harmonic high power RF
Frequency Law
Summing Amplifier
Frequency Law
Generator
Master Oscillator
1.3 MHz - 3.1 MHz
Dipole Search
Coil
Beam Phase Loop
Radial
Loop
Trim
Function
Bunch Length Loop
Existing Fundamental RF System
Phase Shifter
Super-period Phase Splitter
To Other 2nd Harmonic Cavity LPRF Systems
Phase
Modulator
2 RF Level Controller
Func Gen.
2nd Harmonic Cavity Voltage Loop
Func. Gen
Phase Detector (Cavity Lock)
Cavity Lock LPF
2
RF
Detector
RF
Limiters
Phase Detector (Cavity Tune)
2
Gated Summing Amplifier
Delay
Unit
RF Summing Amplifier
Phase
Networks
2
2nd Harmonic Cavity Phase Loop
2nd Harmonic Cavity Tuning
Loop
Digital Signal
Processor
2nd Harmonic Beam Compensation Loop
Sum Electrode
Func. Gen.
Func.
Gen.
LPF
Variable Delay
Variable Gain
Frequency Doubler 2.6
MHz – 6.2 MHz
2nd Harmonic low power RF
HPDCavity
Cavity Bias Regulator
Cavity Bias RegulatorLow Voltage Power Supply
Cavity Lock Servo
Cavity Gap A Voltage Monitor
Summing Amplifier
Phase Modulation and Delay Chassis
1RF 2RF
A single Burle 4648VI tetrode is used to drive the
2RF cavity
Phase LoopALC Loop
Beam Compensation LoopCavity Tuning Loop
PSU - Splat!
+ PSU Tripping + ISIS Schedule + Machine Downtime
2RF Commissioning - Preliminary Results
DHRF Acceleration beam intensity and beam loss (2 x 2RF Cavities)
93.5%
95%
Schematic of fundamental frequency and 2nd harmonic RF lock loop
Var.
90
M. O. Phase Mod
az ±0/ 90( = 0/-18/-36)
Cavity Lock Phase Mod
Trim1 RF.Cav.
Ref.
90
Cavity lock Phase Mod
Trim
Ref.
Var.
Phase Mod
FrequencyDoubler
Fundamental System
2RF System
A
B
az±45PhaseMod Det.
Det.
2 RF.Cav.
Simulated by Cable Delay and Summing Amp
ISIS 2RF System Phase Modulation
2RF5 Shifted For Azithmuthal Position
-1.0000
-0.8000
-0.6000
-0.4000
-0.2000
0.0000
0.2000
0.4000
0.6000
0.8000
1.0000
0 90 180 270 360
Phase (deg 1RF)
Rel
ativ
e V
olts
1RF3
2RF5
2RF4 2RF5 2RF6 2RF8
Az Shift 21.5 73.55 109.5 165.5
1RF Phase 43 147.1 219 331
2RFPhase 86 294.2 438 662
Phase offset for location of each system around ring
-8
-6
-4
-2
0
2
4
6
-5 0 5 10 15
Time (ms)
F-M
od
Vo
lts
2RF4 test
2RF5 test
2RF4 expt
2RF5 expt
0°2RF4-90°
+90°2RF5
8:1 reduction in combined gap volts (simulated!) (SP4+SP5) / (SP4-SP5)
ISIS 2RF System Phase Modulation
-4
-2
0
2
4
6
8
10
-0.005 0.000 0.005 0.010 0.015 0.020
Phase Detector
2RF4 Volts
2RF5 Volts
200V
10kV
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 0.2ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 0.3ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 0.4ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 0.5ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 0.6ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 0.7ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 0.8ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 0.9ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 1.0ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 1.5ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 2.0ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 3.0ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 4.0ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 5.0ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 6.0ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 7.0ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 8.0ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 9.0ms
N - protons
Dual Harmonic Pulses
Animated Version?
DHRF Acceleration with 3 x 2RF cavities
Beam Pulses
@ 9.5ms
N - protons
Theta Phasing Results
2RF SP5 APS Current SP4, 5 & 6 accelerating Theta = 0
Theta
APS Current(with beam) 5Apk
APS Current (no beam) 7Apk
0°
-72°
2RF SP5 APS Current SP4 ,5 & 6 accelerating Theta
Challenges
• Solve Anode PSU tripping problem
• Complete cavity phasing tests
• DHRF Acceleration with all 4 2RF cavities
• Run 2RF Cavities reliably
• Increase beam current!