spx llrf r...feb 06, 2012 · spx0 = r&d system proof of principle (1 sector, 2 cavities)...

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

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

PlannedSPX Location

SPX LLRF R&D ‐ 2/6/2012 ASD Seminar

APS-U SPX System – Zholents’ Transverse RF Chirp Concept1

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)

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

CommonMode

Differential

SPX0 System Performance Requirements 3

SPX LLRF R&D ‐ 2/6/2012 ASD Seminar 3 SPX0 PRD, ICMS# APS_1423800 (1/17/12)

Residual kick

Residual tilt

Low Level Radio Frequency (LLRF) System

CavFieldProbe

Klystron

Controller

Receiver/ Detector

Setpoint

cavRFcav tV cos

Primary responsibility is to regulate the cavity field

tVtV RFQRFI sincos

Polar Coordinates Cartesian Coordinates

22QIcav VVV

QIcav jVV arg

Receiver You can’t regulate any better than your receiver

ADCReference

Cavity Signal

LO CLK

DigitalDownconversion

Analog Front EndDigital Downconversion

sin IF

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

SPX Study Meeting – LLRF T. Berenc 7/27/2010

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

ADC Quantization Noise

)( fSphase noise variance

2log1076.102.6 sfCN

14 bit ADC

dB rad2

deg0032.0 rms

16 bit ADC

dB rad2

852 972

(single sideband spectrum)

deg0008.0

Receiver

ADC Aperture Jitter

Phase noise

rms aperture jitter

)cos())(cos( IFIFIF tt

jitter

fIF=30 MHz

fIF=90 MHz

fIF=150 MHz)log(20 jitterIFjitterSNR

Receiver

)( fSphase noise variance

14 bit ADC, 0.5psec rms

rms30 MHz IF

(single sideband spectrum)

ADC Aperture Jitter

log10)log(20

jitterIFf

90 MHz IFdeg023.0deg008.0

Receiver

Receiver You can’t regulate any better than your receiver

ADCReference

Cavity Signal

LO CLK

DigitalDownconversion

Analog Front EndDigital Downconversion

sin IF

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

July 2011 SPX Workshop

Receiver – Digital Receiver LLRF4 Board – Differential Phase Noise

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

0.09 ~ 35 dB~ 0.023 rms

~ 0.118 rms

Receiver - CW Drift Compensation Demonstration

LLRF 2011 Workshop17

Receiver - Intermodulation Distortion

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

21 2223222

tVVVVVVVVVVVaVa USBLSBUSBoUSBoLSBUSBUSBoLSBUSBUSB cos43

21 2223222

tVVVVVVVVVVVVaVa oUSBoLSBoUSBoLSBoUSBoLSBoo cos23

21 223222

Marki T3-03MQP 5 mixer measurements, Sine vs. Square Drive

5 ”T3 Mixer Primer, A Mixer for the 21st Century”, Ferenc Marki, Christopher Marki, http://www.markimicrowave.com/3436/T3_Mixer_Primer.aspx

Marki T3-03MQP mixer measurements, Sine vs. Square Drive

Estimated‐120dBrad^2/Hz at ‐40dBm input (~10dB < F.S.)

~10dB < F.S.

> 20dB improvement

LBNL/SLAC AFE Ver.1ANL 2‐ChannelDown‐Converter Prototype

~10dB < F.S.

LBNL/SLAC AFE Ver.1

ANL 2‐ChannelDown‐Converter Prototype

+LLRF4

confirmed LBNL/SLAC AFE= ‐120dBrad2/Hz at ‐40dBm

Limited by LLRF4 ADC’swith ANL AFE

Receiver - comparison (Susceptibility to Interference)

CavFieldProbe

Klystron

Controller

Receiver/ Detector

Setpoint

Get to know the plant you are controlling – the cavity (deflecting not accelerating) ….

Longitudinal voltage

Vertical deflecting voltage

yVyV mZ )(

)0(/ yo

180 90 0 90 1800.5

Cavity Transverse VoltageCavity Longitudinal Voltage

Phase (deg)

Magnetic FieldElectric Field

Deflecting Cavity - Beam Loading

Dipole loss factor:

Circuit definition R/Q:CLR

yqq oeq 2

yqV ot

tloss CVkqU

2 24)(

rZloss

Deflecting Cavity - Beam Loading5,6

180 90 0 90 1800.5

Cavity Transverse VoltageCavity Longitudinal VoltageBeam Induced Longitudinal VoltageBeam Induced Transverse Voltage

Phase (deg)

)0( y)0( y

)(2 sjtooo ecjyi

5 Berenc, “An Equivalent Circuit Model ..”, ICMS# APS_14059786 Decker, “..Tilt Monitor”, DIAG-TN-2010-10, ICMS# APS_1417048

tan21/8

dco eIi

0 yVt0 yVt

)(2 sjtooo ecjyi

BBtB IVP cosˆ21

mAIDC 100 MVVcav 5.0

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

* )()(21)()(

sGsG RFRFqqii

* )()(2

sjZjsGsG RFRFqiiq

)tan1(2

tan1cos)()( 222

ZZqqii ss

sRsGsG

)tan1(2sin)()( 222

Zqiiq ss

)tan1(2

)tan1()()( 222

ssssGsG

)tan1(2tan)()( 222

ssssGsG

Polar Coordinates Cartesian Coordinates

RFpolar jZejZN Z ZjCartesian eN

classical “Pedersen/Boussard Equations” Modern I/Q Equations

tIttIttItI RFrIRFrIRFrT sin)(cos)(cos)( ttittitItI RFQRFIRFrT sin)(cos)(cos)(

Polar Coordinates Cartesian Coordinatesfor discussion “NO DETUNING”

Modern I/Q Equations

)(sGiq

)(sGii

)(sGqi

)(sGqq

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

RsGsG Gqq

Gii )()(

)()()()(

sGsGsGsG

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.

)(sG GNiq

)(sGGNqi

)(sG GNqq

)(sGGNii

)(sGBNq

)(sGBNiy

)(sG BNi

)(sGBNqy

drivernoiseI kly

noiseI

drivernoiseQ kly

noiseQ

detnoiseI

detnoiseQ

ns)(sGBN

)(sGBNqn

)(sGBNi

)(sGBNq

Lorentz Force

Detuning

Klystron

Controller Cavity

KlystronController+

Microphonics

I-componentLoop

+ )(sCq

)(sG GNqq

)(sGGNii

drivernoiseI kly

noiseI

drivernoiseQ kly

noiseQ

detnoiseI

detnoiseQ

Q-componentLoop

Cavity

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.

CavFieldProbe

Klystron

Controller

Receiver/ Detector

Setpoint

The Controller….

ControllerUSB interface to host computer

LLRF4 Receiver Chassis Prototype

Controller – Benchtop Tests

Frequency Generation Chassis

351.94 MHz

2815.52 MHz

2756.86 MHz58.66 MHz

Cavity Emulator

Controller – Benchtop Tests

CavityEmulatorout in

LLRF4 + Analog Front End

Out-of-LoopPhase Noise Measurement

FFTAnalyzer

351.94 MHz

2815.52 MHz

2756.86 MHz

Divide by 2CLK

Prescaler

58.66 MHz

Controller – Single System Benchtop Test

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.

sKsC Z

cavset

)(sGqq)(sC

)()(11

cavqq s

sec8.1 d

sec/312 radecav

Controller – Noise Suppression Model

45SPX LLRF R&D ‐ 2/6/2012 ASD Seminar

FFTAnalyzer

351.94 MHz

2815.52 MHz

2756.86 MHz

Divide by 2CLK

Prescaler

58.66 MHz

Divide by 2

CLK Prescaler

Out-of-LoopPhase Noise Measurement

ResidualPhase Noise Test Set

Controller – 2 System Benchtop Test

Freq. Generation Chassis

LLRF Receiver #1

Cavity Emulators#1 and #2

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

LLRF R&D Outlook (overly simplified)

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 …

CommonMode

Differential

SPX0 System Performance Requirements 7

SPX LLRF R&D ‐ 2/6/2012 ASD Seminar 7 SPX0 PRD, ICMS# APS_1423800 (1/17/12)

Residual kick

Residual tilt

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

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

Adaptive Noise Cancellation Concept 9

9 Widrow et. al, “Adaptive Noise Cancelling: Principles & Applications” IEEE Vol. 63, No. 12, Dec. 1975

From [9]

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

Storage Ring RF AM/PM Noise Suppression Concept

Summary

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

spx llrf r...feb 06, 2012 · spx0 = r&d system proof of principle (1 sector, 2 cavities)...

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