SOLEIL New Platform for
Fast Orbit Feedback

Romain BRONÈS, A. Bence, J. Bisou, N. Hubert, D. Pédeau, G. Pichon
Sept. 11Th 2023 - IBIC

1Summary● Context and specifications● New platform insight and installation● Test results● New identification features2

.

Context andspecifications

3

Synchrotron SOLEIL
3rd generation light source●●●

In operation since 2006
France, 20km south of Paris
29 Beamlines in operation

Energy2.75 GeV

Circumference

355 m

Revolution period

1,18 µs

Number of cells

16Beamlines

29Upgrade to SOLEIL II●●●●

4th generationTDR ongoing
Shutdown scheduled for mid-2027
Lower emittance ( < 100 pm.rad)

SOLEILSOLEIL II

Simulation of a source point dimension before andafter the upgrade4

Context and specifications●Upgrade obsolete BPM electronics ahead ofSOLEIL upgrade●Move FOFB application out of the BPM electronics●

Toward a very flexible platform:
follow years of evolutions.

Current BPM electronics: Libera electron

Current PSC: Itest BILT
(correction magnet) Power Supply Controller

Schematic of the current BPM dedicated network

Actual FOFBEvolution

Future FOFB

# BPM122180~200# Corrector

50 H & V

44~60

Data rate

10 kHz

100 kHz

Correction BW

200 Hz

1 kHz

Loop Latency

350 µs

100µs

Stability

10 % of beam size
20 µm H ; 0.8 µm V

2-3% of beam size
50 nm H & VImpact

2024

FOFB running on
new platform

Same performances

2025

Added features

Faster lattice identification.

2026

New BPMelectronics

Loop latency reduced, data rateincreased, correction bandwidth
increased

2028

SOLEIL II, newPSC

Loop latency reduction, dimension
reduction, SOLEIL II performances

2028 + New correction
algorithm

Increased performances5.

New platform insightand installation

6

New platform insight●

New platform: 5 Node systems connected in astar topology●122 BPMs●

100 PSCs

BPM
BPM

BPM

BPM

BPM

BPM

PSC
PSC
PSC

Cell
Node

BPM
BPM
PSC

Cell
Node

PSC
PSC

Central
Node

PSC
PSC
PSC

Cell
Node

BPM
BPM

BPM
BPM

PSC

Cell
Node

PSC
PSC

BPM
BPM

BPM
BPM

7

New platform insightCentral & Cell Nodes
BPM
BPM

BPM

BPM

BPM

BPM

PSC
PSC
PSC

Cell
Node

BPM
BPM
PSC

Cell
Node

PSC
PSC

Central
Node

PSC
PSC
PSC

Cell
Node

BPM
BPM

BPM
BPM

PSC

Cell
NodePSCPSC

BPM
BPM

BPM
BPM

8New platform insight
Cell
NodeCentral & Cell Nodes●

Node system: MTCA chassis
Main part: SoC-FPGA AMC board●Connected by dedicated fibers, SFP module connected to FPGA

●Position and Correction packets inside Ethernet frames, 10 Gbps●

One frame up-down transfer per loop cycle (10 kHz for current BPMs)●

Measured up-down latency < 4,5 µs

PositionsCo
rr ec tions

10 GbE Fiber

Cell
NodeCell
NodeCentral
NodeCell
Node

MTCA chassis Node (front and back)9New platform insightBPM position grabbing
BPM
BPM

BPM

BPM

BPM

BPM

PSC
PSC
PSC

Cell
Node

BPM
BPM
PSC

Cell
NodePSC
PSC

CentralNodePSC
PSC
PSC

Cell
NodeBPM
BPM

BPM
BPM

PSC

Cell
NodePSC
PSC

BPM
BPM

BPM
BPM

10New platform insight
BPM position grabbing●

Ring network of 122 BPMs

Each Cell Node connected to BPM dedicatedcommunication ring (DLS Communication Controller)

BPM
BPM

●

Copper wire SFP module, read only connection●Capture and forward position data of ¼ (~30) of the BPMs

●BPM
BPM

2 GbpsDLS CCCell
Nodesonsiti
PoGroup of position numbered (loop iteration number)
Actual BPM electronics: Libera electron

Cell Node (front)

P.
BPM position IDpacket
1ETH
L1/L2Preamble
7Start Frame Destination
Delimiter
MAC
16Source
MAC

Length62

N Timestamp BPM
ID
18

Ethernet Frame with encapsulated positions packets

2X
Pos.

Y
Pos.

44

repeated

BPM
ID

X
Pos.

Y
Pos.

2

4

4

CRC Interpacket
Gap
max 1522

41211

New platform insight
Correction transmission
BPM
BPM

BPM

BPM

BPM

BPM

PSC
PSC
PSC

Cell
NodeBPM
BPM
PSC

Cell
NodePSC
PSC

CentralNodePSCPSC
PSC

Cell
NodeBPM
BPM

BPM
BPM

PSC

Cell
NodePSC
PSC

BPM
BPM

BPM
BPM

12New platform insight
Correction transmission
●PSC
PSC

Each Cell Node connected ¼ (~25) PSC
in local cell cabinet and three neighbouring cells

PSC

CACTUS: Custom RTM with 32 TX drivers
To be decommissioned with the PSC for SOLEIL II.

●Quick PSC driver switching: current/new platform
Electromechanical relays, powered from central
location.

stion●recCorRegular RJ45-CAT6 cable,
RS422 UART 1.25 Mbps
4 link pairs per cable, 80m max.

Current BPM electronics: Libera electron

CACTUS RTM

Cell Node (back)
Correction
packetPreamble
7Start Frame Destination
Delimiter
MAC
1Cell
NodeCurrent PSC: Itest BILT

●ETH
L1/L2

1.25 Mbps
RS422 UART

6Source
MAC

Length6

2P.
ID

N Timestamp PSC ID Corr.
Value

Ethernet Frame with encapsulated correction packets

repeated

PSC ID Corr.
Value
CRC Interpacket
Gapmax 1522

41213

Installation pictures

Central Node rack cabinet
a. Central Node with outgoing fiber to CellNodes
b. Switch lever and power supplies to relays

A Cell Node rack cabinet
a. Cell Node with fiber connection to Central Node and copper connection to BPMs.
Connections to PSC on the back, not seen.
b. BPM electronics.
c. Power Supply Controller.

A cell rack cabinet
a. Incoming RJ45 CAT6 cable from a Cell Node going to a breakout panel
b. Electromechanical relays. Inputs from RJ45 breakout and BPM electronics,
output to PSC
c. Power Supply Controller.

14

Central Node insight●●

Orbit Response Matrix inversed with SVD,
Tikhonov regularization
Correction controller is an 8 Hz low-pass filter(Perturbation attenuated by inverse of this filter)

BPM+ FA filter

Add a per PSC sine signal●Triggered data capture

PSC

Cell Nodes

Cell Nodes
Sinegenerator

Position
depacketer

MatrixMultiplication

Added functionnalities●Corrector
Magnets

Beam

Correction
controller

Correction
packeter
Serializer

Same current algorithm+Position
data capture

Correction
data capture

Blue dashed rectangle: Central Node detailed correction algorithm.
Yellow blocks show the complete loop

Open loop corrected< Simulation of Transfer function GainInput: sine generator
Output: correction controller

Closed loop15.

Test results

16Machine tests●

Loop successfully closed !
Beam successfully accumulated up to 450 mA
with the new platform running the FOFB

●Mean orbit position PSD
x-plane, 450 mA stored beam.
→ Same performances reached.

●Latency slightly decreased: resonance overshootmoved to higher frequencies

FOFB off
New platform
Old platform

Position PSD and integrated PSD, for x plane.

17Efficiency measurement●

Use on-board sine generator to inject perturbation on one PSC●

Compute Discrete Time Fourier Transform (DTFT)
of mean orbit at this frequency●Repeat at several frequencies, with and without FOFB running●

Compute attenuation factor: 5 at 100 Hz,
overshoot crossover at 400 Hz

FOFB efficiency for several PSC

18

.

New identification
features19

Transfer function identification●

Open loop measurement: corrector not running●

Transfer Function of the overall system:
PSC → CM → Beam → BPM●

Driving 1 PSC at different frequencies.
Capture 100 periods of data.

●

Discrete Time Fourier Transform (DTFT) at each frequency.
→ Obtain TF module and phase●

BPM/PSC gain depends on the ORM●

Select and mean on 10 most significant BPM.
Further normalize by gain at 210Hz.

Bode plot of the measured transfer function. Blue and orange are one horizontal and one vertical PSC respectively.

20

Transfer function identification
Delay observation●

Measured Constant latency of ~ 354/332 µs (X/Y plane)●

At low frequencies: measure uncertainty due to spectral occupation
At high frequencies: phase shift●

The only Y PSC tested shows a phase shift.
We will investigate this behavior on other Y PSC.

●Difference X/Y probably due to the vacuum chamber geometry.

Observing delay vs frequency by PSC. Mean delay with ±std band.

21

Orbit Response Matrix Fast identification●

Open loop measurement: corrector not running●

Driving 10 PSC at 10 different frequencies, 20 Hz spaced●

Perform 10 group captures → get the 100 PSC●

DTFT at each frequency: obtain module and phase●

Deduce ORM coefficients●

Overall capture takes < 2 minutes

PSC

BPM

Driving ten PSCs with different frequencies, observing mean PSC over all BPMs.
Sampling 10 kHz, duration 1.5 s, blackman window.

BPMPSC< Obtained orbit response matrix

22Orbit Response Matrix Fast identification
PSC

Repeatability over 4 measures●Different frequencies, PSC distributions●Max peak to peak = 440 nm/A●

Repeatability will be compared to present DC method

BPM

●

BPM

PSC

Orbit Response Matrix obtained with harmonic analysis. Mean and peak to peak statistics over 4 measures.
Orbit response coefficients distribution, by mean value
and peak to peak statistics over 4 measures.

23

Orbit Response Matrix Fast identification
Measurement corrections●

on angle: compensate constant delay: 354/332 µs (X/Y plane)
Angle of complex coefficient depends to delay and PSC frequency
This is another way to measure constant delay●on module: non constant Transfer Function over the frequency band of measurement.
Each PSC TF estimated by a 1 st order slope
Constant delay
compensation

e2 i π f PSC T delay

Coefficients on the complex plane, before and after delay compensation.

24

Orbit Response Matrix Fast identification

Per BPM observed delay, X (upper) and Y (lower)●Per PSC observed delay, X (upper) and Y (lower)

Observing per BPM and per PSC delay offset from 354/332 µs (X/Y plane)25Orbit Response Matrix Fast identification

Wrong FIR filter

Wrong FIR filter

Per BPM observed delay, X (upper) and Y (lower)

Per PSC observed delay, X (upper) and Y (lower)●Observing per BPM and per PSC delay offset from 354/332 µs (X/Y plane)●

4 BPMs outliers spotted and corrected (wrong FIR filter)

26

Orbit Response Matrix Fast identification

Stainless steel vacuum chamber

Nearby invar footpiece

Per BPM observed delay, X (upper) and Y (lower)

Per PSC observed delay, X (upper) and Y (lower)●Observing per BPM and per PSC delay offset from 354/332 µs (X/Y plane)●4 BPMs outliers spotted and corrected (wrong FIR filter)●

Some PSC show additional latency→ C01 Injection zone, Corrector Magnets over stainless steel vacuumchamber→ C13 Corrector Magnets nearby Invar bpm footpiece●

We will further investigate these PSC with a full Transfer function
identification

Left: regular CM over bellows, Center: C01 CM, Right: C13 CM with Invar yellow footpiece

27From identification to loop model
Simulation and Measurements●Closed-loop model●FOFB efficiency model●

Helpful for future corrector design

PertPSC

RefOrb244+-

M:
InvRespMat

100

100Cor(p)++PertPosSt(p)100

R:
RespMat244

244++244

PosBPM

Higher order, lag-compensation...

TF Measurement (slide 20)

Efficiency Measurement (slide 18)

Efficiency Simulation

FOFB efficiency as computed by model28

Conclusion● The new platform is installed and canoperate during dedicated machine shifts● Loop successfully closed and performancesreached● New features to help diagnostics,

identifications and future developments● Next step: deploy the Control System

devices to allow daily operation(SOFB / FOFB interaction)
Thank you for your attention
29