04
RF System
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 20
The TTF2 / VUV-FEL Linac
Outline
• Overview of RF System• High Power RF - Klystron - Modulator - RF Waveguide Distribution
• Low Level RF Control System - Configuration - Hardware - Software
• Summary
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
VUV-FEL RF System Diagram ACC1 ACC5 ACC4 ACC3 ACC2 ACC6 RF-Gun 3rd harm.
Mod 4 (10 MW)
Mod 5 (5 MW)
Mod 6 (10 MW)
Mod 7 (10 MW)
SMES
Mod 2 (5 MW) Mod 3 (5 MW)Mod 1 (5 MW)
Teststand Hall 2
For Test (Cavities,Couplers, Waveguides)
2 x 5 MW
3.3 MW3.3 MW3.3 MW
3.3 MW 6.7 MW
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Klystrons• 5 MW Klystron THALES TH2104C• 10 MW Multi Beam Klystron THALES TH1801
Operation Frequency: 1.3GHzCathode Voltage: 117kVBeam Current: 131AMax. RF Peak Power: 10MWRF Pulse Duration: 1.5msRepetition Rate: 10Hz
The prototype has been in opera-tion at TTF since May 2000and has 14000h operation hours
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
ModulatorsThe FNAL Modulators
• 3 modulators delivered to TTF byFNAL since 1994
• They are continuously in operationunder different operation conditions
• Comprehensive maintenance duringshutdown, e.g. oil conditioning,cleaning and check of HV
• Improvement of subsystems (e.g. HVswitch, HVPS etc.) are continuing.They are ready for 10Hz operation
The FNAL Modulators
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Modulators (2)Industry made Modulators(PPT Modulator)
• 2 modulators are in operation, have now complete remote controland new RF interlocks (simpler version of the interlock underdevelopment)
• Low leakage inductance pulse transformer (<200µH) resulting inshorter HV pulse rise time of <200µs
HVPS and Pulse Forming Unit Pulse Transformer
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
RF Power Waveguide Distribution• Distribution of klystron output power to the cavities• Protection of the klystron from reflected power• Control of phase and loaded Q
ACC1 ACC3ACC2
ACC4 ACC5
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Cavity Loaded Q and Phase Adjustment
Motorized three stub waveguide tunersused to adjust phases and loaded Q forall cavities
- Improvement from to30°± 3°±
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
RF Control Requirements
• Amplitude and Phase Stability:
- amplitude
- for phase (fast fluctuations)
• Other requirements:- ACC1: cav. 1-4 at 12 MV/m, cav. 5-8 at 20 MV/m phase of accel-erating field -10.8 deg.- 3rd harmonic cavity at 14 MV/m at 183 deg.- S-Band cavity at 2856 MHz phase stability < 1 deg.- RF Gun operation without field probe. rep. rate, pulse length andpower must be variable.
σA A⁄ 104–<
σϕ 0.1°<
Gradient
Power
Detuning
TimePhase
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
RF Control Tasks List
Cavities to be controlled:
• RF gun
• Vector-sum of cryomodule 1
• 3rd harmonic cavity (3.9 GHz) (in 2006)
• Vector-sum of cryomodules in locations 2+3
• Vector-sum of cryomodules in locations 4+5+(6) (in 2006)
• S-Band cavity at 2.856 GHz
• Provide stable phase reference for laser, and diagnostics
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Schematic of the Digital RF System
Tuner
Cavity 1
DirectionalCouplerForward
ReflectedRF
RF
RFLO
LO
LO
DSP/FPGADAC
DAC
I
Q
Tuner
Cavity 8
......8x
Tuner
Cavity 9
Tuner
Cavity 16
......8x
Cryomodule Cryomodule
Klystron Circulator
Power Transmission Line Power Transmission Line
ADC
ADC
ADC
VME
SUN
FieldProbe
IncidentWave
ReflectedWave
Power
Power
fref = 9.02775 MHz÷9
flofrf
frf = 144×fref ≅ 1300 MHz
flo = (144+1/36)×fref ≅ 1300.25 MHz
S&H
-1
TransientDetection
I/Q
VectorModulator
I Q
WaveguideTuner
1 MHz Clock
200kW
4×8 channelADC board14 bit @ 1 MHz
250 kHz
ADC
ADC
ADC
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Digital I/O Detection
mixer
RF
1300 MHzLO
1300.25 MHz
IF250 kHz
time
amlitude
• downconversion of cavity fieldto IF frequency at 250 kHz
• complete phase and amplitudeinformation of the acceleratingfield is preserved.
• sample IF signal at 1MHz rate• subsequent samples describe
real and imaginary componentof the cavity field.
t0 t1
t2 t3
x0
x1
x2
x3
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Control AlgorithmD
AC
DA
C
ReIm
Cavity 32......8x
Cavity 25
klystronvector
modulator masteroscillator
1.3 GHz Cavity 8......8x
Cavity 1
cryomodule 4
...cryomodule 1
. . . .LO 1.3 GHz
+ 250 kHz250 kHz
ADC
f = 1 MHzs
. . . . ...
vector-sumΣ( )ab
a -b
1 8( )ab
a -b
25( )ab
a -b
32( )ab
a -b
DSPsystemsetpoint
tablegaintable
feed
tableforward
++digital
low passfilter
ImRe ImRe ImRe
clock
LO
ADC
LO
ADC
LO
ADC
ImRe
power transmission line
1.3GHzfield probe
04
ware
annels for the control
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 20
Digital Feedback Hard• DSP System- New hardware, faster DSPs (C67), input ch
of 8/16/24 cavities- 8 channel ADC board- 8 channel DAC board- Gigalink interface between boards
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Digital Feedback Hardware (2)
• Downconverter based on AD 8343• RF Gun detectors (forward and reflected power)- AD8347 IQ demodulator (for feedback)- Schotty diode for amplitude (redundant)- HMC precision phase detector (redundant)- AD 8302 for cavity detuning
Gun Control BoxDownconverters
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Digital Feedback Hardware (3)
Gun and ACC1 ACC2, ACC3, ACC4 & ACC5
04
ware
oint, feedback gain and
face
rement, Loaded Q and
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 20
Digital Feedback Soft
• DSP System- Exception detection and handling
• DOOCS DSP Server- Parameter based operation, tables for setp
feedforward calculated by server
• DOOCS Finite State Machine Server- Automated operation, Simple operator inter
• Application tools- Adaptive feedforward, Beam phase measucavity detuning measurement...
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
0.02
0.04
0.06
0.08
30
210
60
240
90
270
120
300
150
330
180 0
Module 1 (ACC1*)
12345678
0.02
0.04
0.06
30
210
60
240
90
270
120
300
150
330
180 0
Module 1 (ACC1*)
1
2
34
567
8
0.02
0.04
0.06
30
210
60
240
90
270
120
300
150
330
180 0
Module 1 (ACC1*)
1
234
5
678
Beam Based Calibration- Good beam required to get sufficient signal (8nC, 30µs, 15MV/m)- Preliminary calibration (to 10%)- Gradient calibration (to 3-5%)
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Exception Handling - Cavity quench detection mechanism (algorithms) - Exception handling procedure
Module 1* at high gradient1-st quench in Cavity 2 2-nd quench in Cavity 6 3-rd quench in Cavity 1 Eacc=19[MV/m] Eacc=21[MV/m] Eacc=24[MV/m]
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Automation of RF Operation
- High degree automation of accelerator operation- Reduce workload of operators- Maximize availability of accelerator
Check/reset interlocks,Find source, check limits...
Adjust feedback loop,
Optimize beam parameters
High voltage is applied,
RF is not permitted
RF_ON
RF_STDBY
HV_ON
Start-up procedureIDLE
Graphical representation of logical dependencies
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Master Oscillator and Frequency DistributionSystem
• Master Oscillator:- Required frequencies:50Hz, 1MHz, 9MHz, 13.5 MHz, 27MHz, 81MHz, 108 MHz, 1.3GHz,1.517GHz, 2.856GHz- Required stability:Within macro-pulse and between macro-pulses: 0.1psLong term: 1ps (minutes), 2ps (hours) 10 ps (days)
• Frequency Distribution:- Temperature stabilized coaxial distribution- Highly stable fiber optic monitoring system
Ayvazyan / Simrock, DESY MAC Meeting, Nov. 9th 2004
Summary
• Commissioning of RF for TTF2 / VUV-FEL is well underway
• All main RF components (klystron / modulator / waveguide) havebeen successfully tested
• LLRF Control System is operational
• New Master Oscillator and frequency distribution are presentlybeing installed and commissioned
• Automation of RF operation under development