ILC GDE Meeting Feb.6,2007
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Transcript of ILC GDE Meeting Feb.6,2007
LLRF
ILC GDE MeetingFeb.6,2007
Shin Michizono
LLRF
- Stability requirements and proposed llrf system- Typical rf perturbations- Achieved stability at FLASH- R&D items- Schedule
- Other comments
2
LLRFStability Requirements for Main Linac
phase tolerance limiting
luminosity loss (deg)
phase tol. limiting incr. in energy spread
(deg)
amplitude tolerance limiting
luminosity loss (%)
amplitude tolerance limiting increase in energy spread (%)
Related fluctuations
correlated BC phase errors .24 .35 HV
uncorrelated BC phase errors .48 .59 Microphonics
correlated BC amplitude errors 0.5 1.8 HV, Ibeam
uncorrelated BC amplitude errors 1.6 2.8 Microphonics
correlated linac phase errors large .36 HV
uncorrelated linac phase errors large 5.6 Microphonics
correlated linac amplitude errors large .07 HV, Ibeam
Uncorr. linac amplitude errors large 1.05 Microphonics
Summary of tolerances for phase and amplitude control. These tolerances limit the average luminosity loss to <2% and limit the increase in RMS center-of-mass energy spread to <10% of the nominal energy spread.
Ref. Mike Church
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LLRFLLRF system configuration at ILC
8 x
MMM
CREV
FWD
KLY
XFMR
ModulatorDriver
LLRF crate 1:- CPU, PS- 3x LLRF- BPM- Timing Distribution- (HOM coupler)
Modulator Control & Interlock (Rack)
Klystron Control, Interlock & Water
Cryogenic Controls (Rack)
REV FWD
2x e--field
Temp (RTD)
Arc (air)
PMT (vac)
Arc
RF Phase Reference Line
WG pressure
Vacuum Controls (Rack)
M M M M M M M MBeamPickup
24x Cavity Probe (plus evt. 48x HOM coupler)
M M M M M M M M
BPM & Magnet
M M M M M M M M
8 x
MMM
CREV
FWD
8 x
MMM
CREV
FWD
8x Coupler
Cryomodule
Accelerator Tunnel
Service Tunnel
Timing & Synchronization
Inter-System Feedback Network/Bus
MPS Network/Bus
RT Control Network
Local Oscillator
LLRF crate 3:- CPU, PS- Motor Controller- Piezo Controller
Temp Temp Temp
Temp
LLRF crate 2:- CPU, PS- Klystron Protection & Interlock Systems
LLRF & Instrumenation Rack
TempPMT
WG pressKlyArc
7xFWD/REV
HOM (1..48x)CavREV (24x)CavFWD (24x)CavProbe (24x)Reference (3x)
BeamPickup (3x)BPM (3x)
48x signal
72x coax
24x fiber
96x Motor
48x Piezo
Temp
WG pressureWG pressure
REV FWD REV FWD
Arc
Po
wer
& H
igh
Leve
l Sig
nal P
ene
trat
ion
RF
& L
ow L
eve
l Sig
nal P
enet
ratio
n
All electronics are located at service tunnelVector-sum control of 26 cavitiesTotal 26x3+6=84ch RF monitors
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LLRFLLRF Rack Detail
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LLRFFB algorithm
26x
26xIn the case of proportional control Output = Gain*Error+FF-> Sufficient dynamic overhead is necessary at high gain operation (>50)
LLRF
Klystron operation point and overhead
@31.5 MV/m operation, llrf overhead is <16.5% in power (8.25% in amplitude)@33 MV/m operation, overhead becomes 11% in power-> It is used for fluctuation compensation, detuning compensation and so on.
0
20
40
60
80
100
0 10 20 30 40 50Pin [W]
Pow
er [
%]
76.5% for cavity input
7% rf distribution loss
16.5% for llrf control*
*neglect all other factors such as HV ripple
Extra rf drive (Gx(error)) is necessary at FB.Proportional FB gain is limited around 80 (when we can pick-up 0.1% error).And the error can be suppressed 1/G=1/80
LLRF
ILC GDE MeetingFeb.6,2007
Shin Michizono
LLRF
- Stability requirements and proposed llrf system- Typical rf perturbations- Achieved stability at FLASH- R&D items- Schedule
- Other comments
8
LLRFSources of Perturbations
o Beam loading o Cavity dynamics
- Beam current fluctuations - cavity filling
- Pulsed beam transients - settling time of field
- Multipacting and field emission
- Excitation of HOMs o Cavity resonance frequency change
- Excitation of other passband modes
- thermal effects (power dependent)
- Wake fields - Microphonics- Lorentz force detuning
o Cavity drive signal- HV- Pulse flatness o Other- HV PS ripple - Response of feedback system- Phase noise from master oscillator - Interlock trips- Timing signal jitter - Thermal drifts (electronics,
power- Mismatch in power distribution amplifiers, cables, power
transmission system)
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LLRFTypical Parameters in a Pulsed RF System
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LLRF
Lorentz Force detuning compensation
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
3.0%
3.5%
4.0%
0 10 20 30 40 50 60detuning [Hz]
addi
tona
l am
plitu
de
Detuning of 30 Hz require additional 2% rf power.
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LLRF
Microphonics
From Thesis of Thomas Schilcher
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LLRFSuppression of fluctuations by FB
*When the system can detect 0.1% error.**only FF
Larger dynamic overhead is desired for the larger FB gain.
Dynamic overhead[%] in power* 0 6 20
FB gain 0 30 100 req.(BC) req.(ML)microphonics &Lorentz force
detuninguncorrerated 30Hz 9.2 0.3 0.09 0.48 5.6 [deg.]
Kly HV stability both 1% 12 0.4 0.12 0.24 0.36 [deg.]
Dynamic overhead[%] in power* 0 6 20
FB gain 0** 30 100 req.(BC) req.(ML)microphonics &Lorentz force
detuninguncorrerated 30Hz 1.28 0.043 0.013 1.6 1.05 [%]
average beamcurrent correated 1% 1 0.033 0.010 0.5 0.07 [%]
Kly HV stability both 1% 1.25 0.042 0.013 0.5 0.07 [%]
Amplitude
Phase
LLRF
ILC GDE MeetingFeb.6,2007
Shin Michizono
LLRF
- Stability requirements and proposed llrf system- Typical rf perturbations- Achieved stability at FLASH- R&D items- Schedule
- Other comments
14
LLRFField Regulation at FLASH
By T. Schilcher
LLRF
ILC GDE MeetingFeb.6,2007
Shin Michizono
LLRF
- Stability requirements and proposed llrf system- Typical rf perturbations- Achieved stability at FLASH- R&D items- Schedule
- Other comments
16
LLRFR&D items
FPGA board development having >26 ADCs RF field stabilities <0.5% in amplitude and <0.24 deg. in phase Crate evaluation (VXI, ATCA, ….)
– Redundancy, board size Software development
– Feedback algorithm
– Klystron linearization
– Exception detection and handling
– Warnings and alarms High IF study
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LLRFDESY SIMCON3.1 Controller
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LLRF
FPGA & DSP boards @KEK
10 16bit-ADCs10 16bit-ADCs
FPGAFPGA
2DACs2DACs
Quench etc.Quench etc.
Output maxOutput max
RF offRF off(by diagnostics in DSP)(by diagnostics in DSP)
Real time intelligent diagnostics by DSP boardReal time intelligent diagnostics by DSP board
Custom FPGA board: Mezzanine card of the commercial DSP board10 16bit-ADCs and 2DACs + 2Rocket IO40 MHz clock
Commercial DSP board (Barcelona) (same to J-PARC system):4x TI C6701 DSPsCan access to FPGA like an external memory of DSP
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LLRFNow, the number of ADCs in a FPGA board is limited due to the substrate. (maybe ~15 with 16 layers in substrate)The idea is based on the ‘digital radio’ and obtaining cavity signals with a ADC.
Mixture of two signals decrease the resolution of analog signals but averaging increases the resolution.
IF1(8 MHz)
IF2(12 MHz)
Triger(48 MHz)
Mixed signal(IF1+IF2)
averaging(IF2 1)-> IF1 signal
averaging(IF1 1)-> IF2 signal
R&D: Proposal of IF mixture
Over-sampling: IF 8 MHz & 12 MHz with 48 MHz sampling Over-sampling: IF 8 MHz & 12 MHz with 48 MHz sampling -> include averaging effect ->increase resolution-> include averaging effect ->increase resolution
Cavity signals do not change during averaging (due to high Q values)→ Enough IF separation
LLRF
ILC GDE MeetingFeb.6,2007
Shin Michizono
LLRF
- Stability requirements and proposed llrf system- Typical rf perturbations- Achieved stability at FLASH- R&D items- Schedule
- Other comments
21
LLRFSchedule
Support for (test) facilities (XFEL,SMTF,STF) Crate evaluation FPGA board development having >26 ADCs. Software development High IF study
I II III IV I II III IV I II III IV
DESY* XFEL design &R&DFPGA board for XFELATCA board developmentConversion of LLRF to ATCAImplement and evaluate ATCA LLRFFinalize LLRF for the XFEL
Software development with SIMCON- DSP
FNAL33 ch FPGA board for ILCTA(NML)Operational Simcon systemATCA development Depending on success with BPM projectFB algorithmhigh IF and sampling
KEK STF- 0.5 STF- 18 cavities vector sum control32ch ADCs FPGA board (ATCA)**ATCA I/ O interlock**IF mixture**24 caivities vector sum
* http:/ / xfel.desy.de/ content/ e154/ upload/ upload_file/ TDR/ XFEL- TDR- Ch- 10.pdf (XFEL TDR)** J FY budget is still unknown.
2007 2008 2009
LLRF
ILC GDE MeetingFeb.6,2007
Shin Michizono
LLRF
- Stability requirements and proposed llrf system- Typical rf perturbations- Achieved stability at FLASH- R&D items- Schedule
- Other comments
23
LLRF
24
LLRF
LLRF
Rf distribution error v.s. max. cavity gradient in case of the 2 cavities
Only rf distribution variation
100
101
102
103
104
105
106
107
108
109
0 5 10 15distribution error [%]
cavi
ty fi
eld
[%]
10% error in rf distribution induces 8.5% higher cavity field
100
100.5
101
101.5
102
102.5
103
103.5
104
104.5
0 2 4 6 8 10 12
Ql error [%]
cavi
ty fi
eld
[%]
10% error in loaded Q induces 4% higher cavity field
Examples: 5%pk-pk Ql variation + 0.2dB (2.3%)pk-pk distribution variation-> 2%+2%=4% cavity field overshoot 31.5*1.04=32.8 MV/m10%pk-pk (1.7%rms)+0.07dBrms (4.6%pk-pk) -> 8% overshoot 34 MV/m
Although Ql and RF distribution ratio control can helpful for flattening each cavity field, This does not work without beam condition.And some residual errors exist due to the imperfect setting.
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LLRFLimitation of coupling adjustment method
By Julien Branlard
Coupling adjustment method does not work at no-beam condition.In order to satisfy both beam/no-beam condition, complex technique (including detuning control) will be necessary.
Vector sum
Lower cavity