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New PS one-turn delay feedbacks and further developments. Thanks to Alfred Blas, Heiko Damerau , Valentin Desquiens , Simone Gilardoni , Guido Sterbini , Letizia Ventura, and all involved people from sections BE-RF-FB, IS and CS. Damien Perrelet BE-RF-FB CERN - PowerPoint PPT Presentation
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New PS one-turn delay feedbacksand further developments
Thanks to Alfred Blas, Heiko Damerau, Valentin Desquiens, Simone Gilardoni, Guido Sterbini, Letizia Ventura, and all involved people from sections BE-RF-FB, IS and CS
Damien Perrelet BE-RF-FB CERN
LIU-DAY 2014, 11 April 2014
Overview of the new feedback board
Current implementations:- PS 10 MHz 1-turn feedback and AVC digital loops- PS transverse damper
Future developments:- PS 1-turn feedback cavities 13/20/40/80 MHz- PS longitudinal coupled-bunch feedback - PSB/AD/LEIR transverse damper upgrade
Summary and outlook
3/21/2014 Damien Perrelet BE-RF-FB CERN 2
Content
RF from BC
Gap Return
DRIVE IN
Power Combiner
1TFB TP
AVC TP
New PS feedback hardware
Power Combiner
CLK DWSTR1
FPGA Stratix II EPS2S90F1020C4
Clock Distri NODLYd UPSTR d nUPSTR d DWSTR1d DWSTR2
4 SERIAL LINKS VME + TRIGGERS
ADC2
ADC1
ADC4
ADC3
LP
LP
LP
LPDAC1
DAC2
DAC3
DAC4LP
LP
LP
LP
ADCs AD6645 DACs AD9754
G Ctrl
LMH6702 AD8009
G Ctrl
G Ctrl
G Ctrl
3/21/2014 Damien Perrelet BE-RF-FB CERN 4
Vprog Test
VGAP DET TP
VPROG TP
Spare
CLK DWSTR2
h200
BP1
SRAM
50 MHz
50 MHz
CLK UPSTR
4 ADC RF INPUT CHANNELS → FPGA → 4 DAC RF OUTPUT CHANNELS
Digital
Electronic board
3/21/2014 Damien Perrelet BE-RF-FB CERN 5
- Generic VME board- STRATIX II FPGA and external SRAM- 4 RF channels ADC and DAC, low latency, 14 bits and running at 105/125 MSPS- 2 multiplexed fine delay lines for glitch-free delay changes (DAC and FPGA clocking)- 4 serial links CVORB or fast 40 Mbit/s
PS 10 MHz cavity feedback overview
3/21/2014 Damien Perrelet BE-RF-FB CERN 7
AVC
1TFB
hn h200
Final amplifier, 2.8-10 MHz cavity, fast wideband FB
Gap returnDrive
H
- Slow voltage control loop (AVC) Gain control at fRF
Reduction of cavity impedanceseen by the beam:
- Fast wide-band feedback around amplifier (internal) Gain limited by delay - 1-turn delay feedback High gain at n frevVprog RF from BC
ADC
ADC
DAC
DAC
Damien Perrelet BE-RF-FB CERN 9
1-turn delay feedback
hn
NOTCH FILTER
COMB FILTER
AUTO DELAY
DACADCVGAP Detected
1TFB OUT to Drive
FPGA
VME INTERFACE
d UPSTR d DWSTR
RF CLK h200
NOTCH BYPASSVPROG
8/4/2014
Suppress the RF componentto not work against AVC
High gain at frev multiples
Cascade of notch + comb
hn
IIR fractional notch hn/hs Periodic comb at frev
Unique sampling clock h200 integer multiple of the revolution frequency
DPRAM
Fine delayed clock
Measurements with beam before LS1
frequency
FB off
10 db/div
FB on
10 db/div
3/21/2014 Damien Perrelet BE-RF-FB CERN 10
Filters only and closed loop transfer functions
Spectrum at cavity gap voltage of a single high intensity bunch 8 10∙ 12 ppb
Beam induced spectrum of four bunches during batch compression
h = 8 13 20
frequency
ampl
itude
h = 8
time
time
Feedbacksuccesfully
follows harmonic changes
Damien Perrelet BE-RF-FB CERN 12
hn
AVC loop and AVC surveillance
3/21/2014
Gap return
Power amplifiers
-
Error[k]+
PIDcontroller
DAC
ADC
Cavity10MHz
ADCnon-IQ detection
CORDICI
Q
Detected gap voltage
Modulator
Drive
RF from beam control
Voltage program
H. Damerau, V. Desquiens, M. Haase, D. Perrelet
VetoRF-FB RF-IS
RF veto
Collaboration
® Amplitude loop only, future phase loop or move to IQ loop® Voltage detection using non-IQ algorithm at given harmonic hn
® High power hardware safety ensured by separate surveillance module
Damien Perrelet BE-RF-FB CERN 13
Digital AVC loop measurement
3/21/2014
® Digital PID with adjustable parameters
® Regulation to full voltage without overshoot in about 15 turns
VprogVdet
ErrorRF drive 100 ms/div 10 ms/div
• Step response of the controller around a cable
500 ms test pulse voltage program Response with fast voltage rise
Error
Vdet
RF drive
Vprog
Error
15 turns
Damien Perrelet BE-RF-FB CERN 14
Installation in the machine
3/21/2014
Four new VME crates installed in building 359 (one for each tuning group)
Example for tuning group B (cavities C56, C66, C76 and C81)
® Full commissioning of the new system during start-up 2014
3/21/2014 Damien Perrelet BE-RF-FB CERN 16
PS transverse feedback
Firmware: A. Blas
1) PU flight time compensation 2) Periodic notch filter for orbit offset suppression3) Hilbert filter for phase compensation at betatron frequencies4) Automatic delay to complete 1 turn
3/21/2014 Damien Perrelet BE-RF-FB CERN 17
PS transverse feedback
10 ns/div
PS TFB ON
10 ns/div
PS TFB OFF
→ Present PS TFB designed to damp 44 μm/turn at 1.4 GeV (BW 23 MHz).
A.Blas, S.Gilardoni, G.Sterbini
Damping of injection errorsDamping of head-tail instability
Damper to cure horizontal and vertical transverse instabilities
See talk by Raymond Wasef
PS 1-turn feedbacks cavities 13/20/40/80 MHz
3/21/2014 Damien Perrelet BE-RF-FB CERN 19
1) Analog conversion to IF and IQ digital processing
→ Using existing and analog frequency conversion boards
or
2) Direct sampling
→ Modification of existing board to achieve higher sampling capabilities
or
→ Build a complete similar new and fast board
Thomas Truszczyński
Frequency conversion board
Mini-PCB to fast ADC adaptation
3/21/2014 Damien Perrelet BE-RF-FB CERN 20
PS longitudinal coupled-bunch feedback
Cross-damping: hdet + hkick = hRF = 21 → Detect at h = 13 and Damp at h = 8
H. Damerau, L. Ventura:
See talk by Letizia Ventura
ADC DACBeam(WCM)
Longitudinal kicker (Finemet)
→ Make a new digital coupled-bunch feedback for the Finemet cavity
• Demonstrated with measurements using existing feedback and the spare cavity
3/21/2014 Damien Perrelet BE-RF-FB CERN 21
Target to other machines:
- Upgrade of PSB, AD and LEIR transverse dampers
PS 10 MHz possible improvements:
- Cavity phase loop or IQ loop (Reliability of RF manipulations)
- Cavity phase compensation (More gain for 1-turn feedback)
- Multi-harmonic RF generation on-board and use of hs=256
Future developments
- New generic feedback board meets requirements → Complex design but easy to use and allows lots of features
- Two operational loops: PS 10 MHz 1-turn feedback and AVC → Fully digital and remote controlled → Commissioning during setting-up 2014
- New operational PS transverse damper → Good results and required for LIU beams
- Many future developments and projects using this hardware → FPGA gives reliability and flexibility for new ideas
3/21/2014 Damien Perrelet BE-RF-FB CERN 22
Summary and outlook
Damien Perrelet BE-RF-FB CERN 23
Thanks for your attention
3/21/2014
Many thanks to people from sections RF/FB-CS and RF/FB/IS for collaboration and support :
Alfred Blas, Philippe Baudrenghien, Andy Butterworth, Heiko Damerau, Valentin Desquiens, Simone Gilardoni, Gregoire Hagmann, Matthias Haase, Wolfgang Hofle, Michael Jaussi, Gerd Kotzian, Tom Levens, Gérard Lobeau, John Molendijk, José Noirjean, Anthony Rey, Maarten Schokker, Guido Sterbini and Letizia Ventura.