The ISIS Dual Harmonic Upgrade

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!


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


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


Animated Version?


Beam Pulses

@ 0.3ms

N - protons


Animated Version?


Beam Pulses

@ 0.4ms

N - protons


Animated Version?


Beam Pulses

@ 0.5ms

N - protons


Animated Version?


Beam Pulses

@ 0.6ms

N - protons


Animated Version?


Beam Pulses

@ 0.7ms

N - protons


Animated Version?


Beam Pulses

@ 0.8ms

N - protons


Animated Version?


Beam Pulses

@ 0.9ms

N - protons


Animated Version?


Beam Pulses

@ 1.0ms

N - protons


Animated Version?


Beam Pulses

@ 1.5ms

N - protons


Animated Version?


Beam Pulses

@ 2.0ms

N - protons


Animated Version?


Beam Pulses

@ 3.0ms

N - protons


Animated Version?


Beam Pulses

@ 4.0ms

N - protons


Animated Version?


Beam Pulses

@ 5.0ms

N - protons


Animated Version?


Beam Pulses

@ 6.0ms

N - protons


Animated Version?


Beam Pulses

@ 7.0ms

N - protons


Animated Version?


Beam Pulses

@ 8.0ms

N - protons


Animated Version?


Beam Pulses

@ 9.0ms

N - protons


Animated Version?


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!

Documents

The ISIS Dual Harmonic Upgrade