spx llrf r...feb 06, 2012 · spx0 = r&d system proof of principle (1 sector, 2 cavities)...
TRANSCRIPT
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SPX LLRF R&D
Feb. 6, 2012ASD Seminar
ANL: Tim Berenc, Hengjie Ma, Ned Arnold, Frank Lenkszus, Tom Fors, Bill Yoder
LBNL: Larry Doolittle, Gang Huang, John Byrd,Jim Greer, Kerri Campbell
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Outline
Intro LLRF Receiver (prototype results) Deflecting Cavity Behavior (static and dynamic) LLRF Controller (benchtop performance tests) Storage Ring RF modification plans Summary
Advanced Photon Source Upgrade (APS‐U) project
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PlannedSPX Location
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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APS-U SPX System – Zholents’ Transverse RF Chirp Concept1
4
Goal: provide ~2 psec (presently 50‐100 psec) X‐ray pulses at 6.5 MHz rep. rate for time‐resolved studies
Ideally, second cavity exactly cancels effect of first cavity
1 A. Zholents et al., NIM A 425, 385 (1999)
Correlation between vertical distribution of x‐rays and time‐distribution of electrons that generated them. Pulse can be sliced or compressed with an asymmetric cut crystal.
RF at ~2815 MHz(8th harmonic of Storage Ring RF)
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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SPX0 = R&D System Proof of Principle (1 Sector, 2 cavities) Cavities counter‐phased (180deg) to demonstrate tolerance requirements Cavities run in‐phase to create a chirped beam around entire ring to have a look at short pulse x‐rays
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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CommonMode
Differential
SPX0 System Performance Requirements 3
6
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar 3 SPX0 PRD, ICMS# APS_1423800 (1/17/12)
Residual kick
Residual tilt
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Low Level Radio Frequency (LLRF) System
CavFieldProbe
Klystron
Controller
Receiver/ Detector
Setpoint
LLRF
cavRFcav tV cos
Primary responsibility is to regulate the cavity field
tVtV RFQRFI sincos
Polar Coordinates Cartesian Coordinates
22QIcav VVV
QIcav jVV arg
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Receiver You can’t regulate any better than your receiver
ADCReference
Cavity Signal
ADC
LO CLK
DigitalDownconversion
Analog Front EndDigital Downconversion
cos
sin IF
IF
IF
RF
RF
I
Q
I
Q
Digital Receiver
Ref. PhaseLock Loop
Regulate to a Designated Phase Reference
• Don’t let the LO assume the role of the phase reference• Phase is a Differential Measurement• Mixers preserve phase information, x’s and ÷’s preserve timing• In theory, common mode LO and clock noise cancels
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SPX Study Meeting – LLRF T. Berenc 7/27/2010
1221
12 2
22
N
q
ADC Quantization Noise
Variance
N = # of ADC bits
CNSNR 76.102.6
C = dB carrier is below full scale
[dB]22/ so fN
2log1076.102.6 sfCNdB
Receiver
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SPX Study Meeting – LLRF T. Berenc 7/27/2010
ADC Quantization Noise
dB ra
d2/Hz
)( fSphase noise variance
2log1076.102.6 sfCN
0
max
0
2 )(f
dffS
14 bit ADC
dB rad2
deg0032.0 rms
16 bit ADC
dB rad2
rms
852 972
(single sideband spectrum)
deg0008.0
Receiver
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SPX Study Meeting – LLRF T. Berenc 7/27/2010
ADC Aperture Jitter
Phase noise
rms aperture jitter
[dB]
)cos())(cos( IFIFIF tt
jitter
fIF=30 MHz
fIF=90 MHz
fIF=150 MHz)log(20 jitterIFjitterSNR
Receiver
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SPX Study Meeting – LLRF T. Berenc 7/27/2010
dB ra
d2/Hz
)( fSphase noise variance
0
max
0
2 )(f
dffS
14 bit ADC, 0.5psec rms
rms30 MHz IF
rms
(single sideband spectrum)
ADC Aperture Jitter
32
log10)log(20
s
jitterIFf
90 MHz IFdeg023.0deg008.0
Receiver
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Receiver You can’t regulate any better than your receiver
ADCReference
Cavity Signal
ADC
LO CLK
DigitalDownconversion
Analog Front EndDigital Downconversion
cos
sin IF
IF
IF
RF
RF
I
Q
I
Q
Digital Receiver
Ref. PhaseLock Loop
Regulate to a Designated Phase Reference
• Don’t let the LO assume the role of the phase reference• Phase is a Differential Measurement• Mixers preserve phase information, x’s and ÷’s preserve timing• In theory, common mode LO and clock noise cancels
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July 2011 SPX Workshop
14
CLK
IF
Receiver – Digital Receiver LLRF4 Board – Differential Phase Noise
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
drift
Receiver - CW Drift Compensation4
4 “Signal Processing for High Precision Phase Measurements”, G. Huang, L. Doolittle, J. Staples, R. Wilcox, J. Byrd , Proceedings of BIW10
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0.09 ~ 35 dB~ 0.023 rms
~ 0.118 rms
5
Receiver - CW Drift Compensation Demonstration
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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LLRF 2011 Workshop17
Receiver - Intermodulation Distortion
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33
221 iiioo vavavaav
For simplicity assume a Taylor series approximation (in general should use Volterra series)
For a 3‐tone input signal: o : RF carrier: Lower side‐band cal‐toneLSB
: Upper side‐band cal‐toneUSB
oUSBLSBo
tVVVVVVVVVVVaVav LSBUSBLSBoLSBoUSBLSBUSBoLSBLSBLSBo cos43
41
21 2223222
31
tVVVVVVVVVVVaVa USBLSBUSBoUSBoLSBUSBUSBoLSBUSBUSB cos43
41
21 2223222
31
tVVVVVVVVVVVVaVa oUSBoLSBoUSBoLSBoUSBoLSBoo cos23
41
21 223222
31
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Receiver - Intermodulation Distortion
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Marki T3-03MQP 5 mixer measurements, Sine vs. Square Drive
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Receiver - Intermodulation Distortion
5 ”T3 Mixer Primer, A Mixer for the 21st Century”, Ferenc Marki, Christopher Marki, http://www.markimicrowave.com/3436/T3_Mixer_Primer.aspx
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Receiver - Intermodulation Distortion
Marki T3-03MQP mixer measurements, Sine vs. Square Drive
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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Receiver - Intermodulation Distortion
Marki T3-03MQP mixer measurements, Sine vs. Square Drive
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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Estimated‐120dBrad^2/Hz at ‐40dBm input (~10dB < F.S.)
~10dB < F.S.
> 20dB improvement
LBNL/SLAC AFE Ver.1ANL 2‐ChannelDown‐Converter Prototype
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~10dB < F.S.
LBNL/SLAC AFE Ver.1
ANL 2‐ChannelDown‐Converter Prototype
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ANL 2‐ChannelDown‐Converter Prototype
+LLRF4
confirmed LBNL/SLAC AFE= ‐120dBrad2/Hz at ‐40dBm
Limited by LLRF4 ADC’swith ANL AFE
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Receiver - comparison (Susceptibility to Interference)
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Low Level Radio Frequency (LLRF) System
CavFieldProbe
Klystron
Controller
Receiver/ Detector
Setpoint
LLRF
Primary responsibility is to regulate the cavity field
Get to know the plant you are controlling – the cavity (deflecting not accelerating) ….
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Longitudinal voltage
Vertical deflecting voltage
yVyV mZ )(
o
mt
VjV
)0(/ yo
180 90 0 90 1800.5
0
0.5
Cavity Transverse VoltageCavity Longitudinal Voltage
Phase (deg)
Vol
tage
Magnetic FieldElectric Field
Time
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Deflecting Cavity - Beam Loading
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Dipole loss factor:
Circuit definition R/Q:CLR
Vt
yqq oeq 2
2
C
yqV ot
22
21
tloss CVkqU
22
2 24)(
yQR
UyV
qUk o
rZloss
8.17
2
2
UV
QR
r
t
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Deflecting Cavity - Beam Loading
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Deflecting Cavity - Beam Loading5,6
29
180 90 0 90 1800.5
0
0.5
Cavity Transverse VoltageCavity Longitudinal VoltageBeam Induced Longitudinal VoltageBeam Induced Transverse Voltage
Phase (deg)
Vol
tage
)0( y)0( y
)(2 sjtooo ecjyi
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
5 Berenc, “An Equivalent Circuit Model ..”, ICMS# APS_14059786 Decker, “..Tilt Monitor”, DIAG-TN-2010-10, ICMS# APS_1417048
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222
tan21/8
scav
B
r
mo
cav
B
o
tg P
Pf
ffQPP
QQR
VP
2221
2 tof
dco eIi
0 yVt0 yVt
)(2 sjtooo ecjyi
BBtB IVP cosˆ21
mAIDC 100 MVVcav 5.0
Deflecting Cavity - Beam Loading
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
31For example: see P. Wilson, SLAC-PUB-2884, p. 26, prob 4.4
ttittitItI RFQRFIRFrT sin)(cos)(cos)(
ZRFQZRFIZRFrcav ttvttvtVtV sin)(cos)(cos)(
Deflecting Cavity – Dynamic Behavior
In‐general I/Q modulations of IT each cause both I/Q modulations of Vcav
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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*
* )()(21)()(
NsjZ
NsjZ
sGsG RFRFqqii
*
* )()(2
)()(N
sjZN
sjZjsGsG RFRFqiiq
Deflecting Cavity – Dynamic Behavior
)tan1(2
tan1cos)()( 222
2
Z
ZZqqii ss
sRsGsG
)tan1(2sin)()( 222
Z
Zqiiq ss
RsGsG
)tan1(2
)tan1()()( 222
2
Z
Z
ssssGsG
)tan1(2tan)()( 222
Z
Z
ssssGsG
Polar Coordinates Cartesian Coordinates
RFj
RFpolar jZejZN Z ZjCartesian eN
classical “Pedersen/Boussard Equations” Modern I/Q Equations
tIttIttItI RFrIRFrIRFrT sin)(cos)(cos)( ttittitItI RFQRFIRFrT sin)(cos)(cos)(
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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Deflecting Cavity – Dynamic Behavior
Polar Coordinates Cartesian Coordinatesfor discussion “NO DETUNING”
Modern I/Q Equations
)(sGiq
)(sGii
)(sGqi
)(sGqq
GTiiI
GTqiI
s
YsGsG GG 1)()(
0)()( sGsG GG
Y = Beam Loading Factor which can be negative for deflecting cavities. Amp/Phase control can be lost when beam offset drives the cavities to full field (there is no drive carrier). This doesn’t happen for I/Q control.
for discussion “NO DETUNING”
0)()( sGsG Giq
Gqi
s
RsGsG Gqq
Gii )()(
)()(
)()()()(
)()(
sIsI
sGsGsGsG
sVsV
GQ
GI
Gqq
Gqi
Giq
Gii
GQ
GI
Use vector projection techniques to find the transfer functions from generator current and beam current modulations. Generator Current in‐phase modulation is shown here. Total of 15 transfer functions describe the cavity.
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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Deflecting Cavity – Dynamic Behavior
m
)(sG GNiq
)(sCq
)(sCi
)(sL
)(sGGNqi
)(sG GNqq
)(sGGNii
ny
)(sGBNq
)(sGBNiy
nzy
)(sNi
)(sNq
)(sG BNi
)(sGBNqy
setI
setQ
drivernoiseI kly
noiseI
drivernoiseQ kly
noiseQ
detnoiseI
detnoiseQ
ns)(sGBN
i
)(sGBNqn
)(sGBNi
)(sGBNq
IV
QV
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Deflecting Cavity – Dynamic Behavior
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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Deflecting Cavity – Dynamic Behavior
Lorentz Force
Detuning
Klystron
+
+
m
Controller Cavity
+
-
KlystronController+
-
Microphonics
I-componentLoop
+ )(sCq
)(sCi
)(sL
)(sG GNqq
)(sGGNii
)(sNi
)(sNq
setI
setQ
drivernoiseI kly
noiseI
drivernoiseQ kly
noiseQ
detnoiseI
detnoiseQ
Q-componentLoop
Cavity
IV
QV
No cross‐coupling when cavity is tuned to resonance,except through Lorentz Force Detuning (minimal if stiff cavity)
Pursue R&D benchtop tests with a cavity emulator to quantify the LLRF system contribution to the system error budgets.
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Low Level Radio Frequency (LLRF) System
CavFieldProbe
Klystron
Controller
Receiver/ Detector
Setpoint
LLRF
Primary responsibility is to regulate the cavity field
The Controller….
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SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
ControllerUSB interface to host computer
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LLRF4 Receiver Chassis Prototype
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Controller – Benchtop Tests
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40
BPFx8
1/6
LO
Frequency Generation Chassis
351.94 MHz
REF
2815.52 MHz
2756.86 MHz58.66 MHz
Cavity Emulator
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Controller – Benchtop Tests
Frequency Generation Chassis
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LO
ch2
ch1
LLRF4
ch3
CLK
OUT 1
LO
LO
CavityEmulatorout in
tune
cal
ch4
LLRF4 + Analog Front End
Out-of-LoopPhase Noise Measurement
FFTAnalyzer
BPFx8
1/6
LO
Frequency Generation Chassis
351.94 MHz
REF
2815.52 MHz
2756.86 MHz
Divide by 2CLK
Prescaler
58.66 MHz
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
Controller – Single System Benchtop Test
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Noise sources include an independent LO generator used for cavity emulator. This is not something that exists in the ‘real’ system.
What matters is the noise suppression capability in combination with our expected noise sources.
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What matters is the noise suppression capability in combination with our expected noise sources.
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ssK
sKsC Z
PZ
P1)(
cavset
E
)(sGqq)(sC
dse
dsqqE
cav
esGsC
)()(11
cav
cavqq s
sG
)(
sec8.1 d
2PK
sec/312 radecav
Controller – Noise Suppression Model
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45SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
LO
ch2
ch1
LLRF4
ch3
CLK
OUT 1
LO
LO
CavityEmulatorout in
tune
cal
ch4
LLRF4 + Analog Front End
FFTAnalyzer
BPFx8
1/6
LO
Frequency Generation Chassis
351.94 MHz
REF
2815.52 MHz
2756.86 MHz
Divide by 2CLK
Prescaler
58.66 MHz
LO
ch2
ch1
LLRF4
ch3
CLK
OUT 1
LO
LO
CavityEmulatorout in
tune
cal
ch4
LLRF4 + Analog Front End
Divide by 2
CLK Prescaler
Out-of-LoopPhase Noise Measurement
ResidualPhase Noise Test Set
Controller – 2 System Benchtop Test
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Freq. Generation Chassis
LLRF Receiver #1
Cavity Emulators#1 and #2
46
ResidualPhase Noise Test Set
(measure noise between cavity emulators)
LLRF Receiver #2
Price paid for capability tosuppress low freq. noise
(i.e., beam loading & microphonics)
LLRF System contribution~ 20 fsec rms [0.1 Hz – 1MHz]
Controller – 2 System Benchtop Test
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LLRF R&D Outlook (overly simplified)
47
Adding the calibration tone scheme into the cavity control gateware. Currently these are 2 separate code bases, parts need to be merged.
Preparing for real single cavity testing to begin ~ June 2012
Modifications to Storage Ring RF System …
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CommonMode
Differential
SPX0 System Performance Requirements 7
48
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar 7 SPX0 PRD, ICMS# APS_1423800 (1/17/12)
Residual kick
Residual tilt
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49
Present Storage Ring Beam Jitter 8
22 5.17.065.1~
22 5.07.086.0
22 15.07.072.0
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar8 Sereno et. al, “Storage Ring Phase Noise Studies …” AOP-TN-2012-001
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Horizontal BPM Data
Feed Forward OFF
Feed Forward ON
AM & PM suppression at Both Stations
Experiment with 360Hz Feed‐Forward correction of Storage Ring Klystron High‐Voltage Power Supply (HVPS) induced noise
Proof of Principle Feed Forward Experiment
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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51
Adaptive Noise Cancellation Concept 9
9 Widrow et. al, “Adaptive Noise Cancelling: Principles & Applications” IEEE Vol. 63, No. 12, Dec. 1975
From [9]
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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Adaptive Noise Cancellation Concept 9
From [9]
9 Widrow et. al, “Adaptive Noise Cancelling: Principles & Applications” IEEE Vol. 63, No. 12, Dec. 1975
tNtN NQNI sincos
22 )()( QQII NYNY
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53
Storage Ring RF AM/PM Noise Suppression Concept
SPX LLRF R&D ‐ 2/6/2012 ASD Seminar
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Summary
54
Digital LLRF system shows promise of femto‐second level synchronization [0.1 Hz – 1MHz]with proper attention to common source distribution
Great design improvement demonstrated for Analog Front End with T3 mixers
New I/Q small‐signal baseband model developed for SRF Deflecting Cavities
Adaptive noise cancellation of Storage Ring main 352MHz RF system AM/PM noise is being pursued to reduce present beam jitter