1. Orbit Feedback System Development for the TLS and Planning for the TPS
Kuo-Tung Hsu
on behalf of the Orbit Feedback Team
NSRRC XBPM and Beam Stability Mini-Workshop
September 11-12, 2008
NSRRC, Hsinchu 30076, Taiwan

2. Orbit Feedback System Development for the TLS

3. Outlines
Current status of the orbit feedback system for TLS
Upgrade project
Purpose of the upgrade
BPM electronic upgrade
Corrector power supply upgrade
XBPM integration plan
Orbit feedback system to fast orbit feedback migration
Feedback loop simulation and modeling
As TPS FOFB testbed

4. Current Status of the Orbit Feedback System for TLS
Orbit feedback system was deployed in 1996.
Switched electrodes BPM electronics support only for closed orbit measurement
Old linear type power supply
=> Heavy (maintenance is no easy)
=> The regulator loop of the power supply is modified to remove noise at high frequency (eliminate noise of IR BL) => reduced its bandwidth.
Original feedback computation is done by a VME ‘C40 DSP board
Migrate to PowerPC VME module to simply maintenance and upgrade
Achieved orbit performance ~ 1 mm (in DC sense)
Cannot remove high frequency orbit noise!
Girder vibration, power supply noise/ripples
Insertion devices gap/phase move speed is limited.

5. Current Status of the Orbit Feedback System for TLS
1996
DSP Program Development PC
Windows 2000/Code Composer Studio 2.0
Control
Consoles
Control
Network
JTAG Interface
Orbit Acquisition
VME Crate
Reflective Memory
Hub
Corrector Control
VME Crate
1 kHz sampling V M E H O S T
RM/
DMA 16
Bit A D C 16
Bit A D C 16
Bit A D C V M E H O S T
DSP
Board
DSP
Develp.
Adapter
RM/
DMA 16
Bit D A C 16
Bit D A C 16
Bit D A C
Timing Generator
DSP +
MVME-147 CPU
1995~1998:
DSP Program Development Environment
JTAG adapter
Windows95/98
1998~2002
Ethernet based JTAG adapter
Windows 98/2000
Correction Magnet Power Supply
Electron BPM

6. Current Status of the Orbit Feedback System for TLS
Orbit Feedback System Upgrade, June 8, 2001
Control
Consoles
Control
Network
Orbit Acquisition
VME Crate
Reflective Memory
Hub
Corrector Control
VME Crate
1 kHz sampling V M E H O S T
RM/
DMA 16
Bit A D C 16
Bit A D C 16
Bit A D C
Timing Generator V M E H O S T
RM/
DMA V M E H O S T
RM/
DMA 16
Bit D A C 16
Bit D A C 16
Bit D A C
VME
Crate
PowerPC
CPU
PowerPC
CPU
1991~1998: MVME-147/ pSOS+
1998~2005: CES RIO2-8060/8062, RIO3-6064/ LynxOS2.4, 3.1, 4.0 migration
2005: PPC CPU/ LynxOS2.4, 3.1, 4.0
Correction Magnet Power Supply
Electron BPM

7. Eliminate orbit leakage of a dynamic local bump (EPBM, ~ several Hz)
Step Response of the Feedback Loop
Eliminate Orbit Excursion for the operation of U5
Feedback OFF
Feedback ON
Eliminate orbit leakage of a dynamic local bump (EPBM, ~ several Hz)
Feedback OFF
Feedback ON

8. Reasons for the FOFB Migration
Orbit feedback system was deployed twelve years ago (1996).
Response time is limited by
Limited power supply bandwidth
BPM performance
Eddy current effect of the vacuum chamber still no a limit!
Horizontal ~ 20 Hz
Vertical ~ 80 Hz
Perturbation from fast sources cannot be removed effectively
~ 20 Hz mechanical vibration
Fast operation of insertion devices
Power supply noise
Enhance functionalities to support various study
Used as testbed to exercise various TPS orbit stabilization techniques

9. Upgrade Plan in the Orbit Feedback
Approaches
BPM upgrade
MX-BPM -> Libera Brilliance
Better performance, rich functionalities
Corrector PS upgrade
Wide bandwidth, easy maintenance, low noise
Obit feedback system infrastructure upgrade
Planed bandwidth increase
Horizontal ~ 50 Hz
Vertical ~ 100 Hz
R&D of various issues for fast orbit feedback techniques
Possible use the system as test-bed for beam stabilization system for Taiwan Photon Source.

10. Components for the Orbit Feedback System
BPM
New generation BPM electronics (10 kHz update rate, > 1 kHz BW)
Orbit measurement
Slow orbit measurement > 10 times/sec to control servers/consoles.
Fast orbit acquisition for feedback purpose
~ 10 kS/sec, sync by event system.
Share orbit information among feedback processors via a dedicated fiber link
Block data capture is included for diagnostic purposes
Corrector control
Digital power supply is preferred for feedback corrector control
GbE interface for fast corrector setting by UDP broadcasting
~ 10 k update/sec
~ 16 bit control resolution
Historical recording is included for diagnostic purposes
Feedback Processor and Algorithm
PPC Feedback engine + LynxOS
Various control rules can be chosen
Fast orbit feedback => dedicated feedback system
Corrector maximum steered angle :
~ 1 mrad (< 10 Hz)
~ Hz

11. New BPM Integration Structure – Original Plan
TLS Control Network xx
To minimize the efforts for TPS EPICS efforts -
TLS will integrated the EPICS devices
Control Console
EPICS
OPIs and Clients
Control Console
Control Console
EPICS
broadcast
ILC
ILC
FOFB
Corrector
Control
FB Node
VME RM
改為 PMC RM
ILC
ILC
Gateway
ILC10 to
TLS ILC
database
EPICS
Gateway
ILC
ILC07
VME RM
完成後移除
Diag.
Node RM
Network
TPS Control System Development Network
EPICS
Gateway
ILC12
完成後移除
VME RM
EPICS
Data Acq
Node #1
Data Acq
Node #N
Why Libera embedded EPICS IOC?
Avoid duplicate efforts for TPS project
SA Ethernet Switch
N=1, 2, 3, 6 ?
Libera
Brilliance
X 59
R1 BPM (10)
R2 BPM (10)
R3 BPM (11)
R4 BPM (10)
R5 BPM (10)
R6 BPM (8)

12. Components for the Fast Orbit Feedback System - Original Plan -
WS/Unix
PC/Linux
PC/Linux
Control
Consoles
Control
Network
N=1, 2, 3, 6 ?
Reflective Memory
Hub
Diagnostics Node V M E H O S T
PMC RM V M E H O S T
PMC RM V M E H O S T
PMC RM 16
Bit D A C 16
Bit D A C V M E H O S T 16
Bit D A C 16
Bit D A C 16
Bit A D C 16
Bit A D C V M E H O S T V M E H O S T
PMC RM
PMC RM
PMC RM V M E H O S T
PMC RM V M E H O S T
PMC RM
VME Host PowerPC 7410
GbE Interface
Fast Orbit Feedback VME
Corrector DC Control
Libera Group #1
Libera Group #2
Trigger
Libera Group #3
PS Control
Summing Amplifier
Libera Group #4
Libera Group #5
Libera Group #6
Super-period 1, 2, 3, 4, 5, 6 BPM
Correction Magnet Power Supply
January 11, 2008

13. Challenge: Fast Access from BPM
GbE Communication Jitter Test for Libera on the PowerPC/LynxOS 4.0 Environment
Challenge: Fast Access from BPM
PowerPC
DA converter
PowerPC/LynxOS 4.0 RTOS
Oscilloscope
1 Libera
2 Liberas
6 Liberas
Change state when received a GbE UDP package
7 Liberas

14. Solutions: GbE Libera Grouping and Planned XBPM Interface
Goal: to reduce communication overhead
Master Link
(To Fast Orbit Feedback System)
Uni-direction GigE (UDP Package for one group data)
Redundancy Link
(To Fast Orbit Feedback System)
Slave
Slave
Master
Slave
Libera Grouping (1 ~ 64 units?)
Multi-gigabits bidirectional links
BPM
Finally GbE Libera Grouping : up to 64 Libera (one UDP package)
Latency < 30 msec for 64 group members

15. TPS Control System Development Network
TLS Libera Brilliance Migration ( )
Control Console
TLS Control System
+ EPICS OPI
TLS Control Network xx
EPICS
OPIs and Clients
Control Console
CA, LabCA
Control Console
EPICS
ILC
broadcast
ILC
ILC
ILC
ILC
FB Node
(VME RM)
Gateway
ILC10 to
TLS ILC
database
Router
TPS Control System Development Network RM
Network
EPICS
ILC12
Corrector Control
VME RM
CSPI Interface
Data Acq
Node
Diagnostic
Node
(Under Construction)
SA Ethernet Switch
Multi-Gigabit Link xx
Control & Sync.
Libera
Brilliance
X 59
R1 BPM (10)
R2 BPM (10)
R3 BPM (11)
R4 BPM (10)
R5 BPM (10)
R6 BPM (8)

16. TLS Libera Brilliance Migration (2008.08)
Using CSPI to access the BPM data
New functionality will development at EPICS environment
New control consoles for the TLS will support the environment of the TLS control system as well as EPICS toolkits
- Configuration
- Turn-by-turn
- Decimated turn-by-turn
- Post-mortem
One GbE grouping for the 10 kHz data rate access to minimize the resources required for the data acquisition and feedback
Load of one CPU board to handle 10 kHz rate is still OK for ~ 60 set of BPMs
Reliability experiences: 16 members of Libera Brilliance running since early May until July, 64 members Libera running from early July, no single fault up to now!

17. New Power Supply for Corrector
Power Supply Performance Comparison
Reasons for this upgrade
Maintenance
Performance
Upgrade of the TLS corrector power supplies system at
January 2007 for vertical plane
October 2008 for horizontal plane
The performance of linear (old) and switching (new) power supply in standard deviation. The standard deviation of 0.6 mA of vertical plane power supplies are due to analog-to-digital data acquisition module performance.
Old PS for horizontal correctors
New PS for vertical correctors
New PS for vertical correctors
Old PS for horizontal correctors
Measured integrated noise from DC~100 Hz ~ 10 nrad

18. Some Observation by New BPM during Top-up Injection Instance
Due to injection septum field leakage
Full-cycle sine septum power supply is in planning to replace the half-sine power supply by the Injector Group
Power supply ripples
Shape is similar
Position dependent of BPM sum signal < 0.5%
Cycle N Injection
Cycle N+1 Injection
Top-up injection
302 mA
Gain of the charging power supply need adjust
301 mA

19. Beam Spectrum Observed by Libera Prototype Test
Upgrade of the TLS orbit feedback system is schedule in 2008.
Practice all necessary techniques at TLS
Quadrupole Vibration Spectrum
(Horizontal)
R1BPM8 Observation (Libera Electron)
Horizontal Position Spectrum
After removed some found sources (Hor.)
Vertical Position Spectrum
Horizontal Integrated Displacement
Vertical Integrated Displacement

20. Components for the Fast Orbit Feedback System Current Configuration
WS/Unix
PC/Linux
PC/Linux
Control
Consoles
Control
Network
10 kHz Rate Data Acquisition
Reflective Memory
Hub
1 kHz sampling
Diagnostics Node
10 kHz Rate Data Acquisition V M E H O S T V M E H O S T
PMC RM
RM/
DMA V M E H O S T
RM/
DMA 16
Bit D A C 16
Bit D A C 16
Bit A D C 16
Bit A D C V M E H O S T
PMC RM
VME Host PowerPC 7410
GbE Interface
GbE Interface
Fast Orbit Feedback VME
Libera Group R1
10 kHz sampling
Libera Group R2
Trigger
Libera Group R3
Correction Magnet Power Supply
Libera Group R4
Libera Group R5
Libera Group R6
Super-period 1, 2, 3, 4, 5, 6 BPM
January 11, 2008

21. OLD BPM System NEW BPM System 2008.08.25
Horizontal Beam Position (Feedback ON)
OLD BPM System
NEW BPM System
No intensive tuning was performed after BPM migration!

22. OLD BPM System NEW BPM System 2008.08.25
Vertical Beam Position (Feedback ON)
OLD BPM System
NEW BPM System

23. TLS orbit log (0.1Hz sampling)
2008/08/29
One of a slide of Dr. C.C. Kuo mm mm mm mm mm
K.T. Hsu will talk about high frequency behavior

24. Components for the Fast Orbit Feedback System Final Configuration
WS/Unix
PC/Linux
PC/Linux
Control
Consoles
Control
Network
XBPM
Data Acqiuisition
10 kHz Rate Data Acquisition
10 kHz sampling
Diagnostics Node
Reflective Memory
Hub
10 kHz Rate Data Acquisition V M E H O S T V M E H O S T
PMC RM 16
Bit D A C 16
Bit D A C V M E H O S T 16
Bit D A C 16
Bit D A C 16
Bit A D C 16
Bit A D C V M E H O S T V M E H O S T
PMC RM
PMC RM
PMC RM
VME Host PowerPC 7410
GbE Interface
GbE Interface
Fast Ethernet Interface
Fast Orbit Feedback VME
Corrector DC Control
Libera Group R1
Libera Group R2
Trigger
Libera Group R3
PS Control
Summing Amplifier
Libera Group R4
Ethernet Switch
Libera Group R5
Libera Group R6
XBPMs
Super-period 1, 2, 3, 4, 5, 6 BPM
1 kHz Rate Data Acquisition
Correction Magnet Power Supply

25. FOFB Feedback Loop Simulation
Reference Orbit P + UT
W-1 V
Corrector I - D
Response Matrix R = V * W * UT
Accelerator
Vacuum
Chamber
BPM +
Measured Orbit +
Measured Noise
Orbit Disturbance
due to various sources
Orbit
squad vib = 1 mm, sBPM noise = 0.25 mm, sCorr noise = 10 nrad

26. FOFB Feedback Loop Simulation – cont.
Quadrupole Vibration Effect
Power Noise Study
squad vib = 1 mm
sCorr noise = 10 nrad
Static Feedback Effectiveness
Feedback Loop Frequency Response Study
squad vib = 1 mm, sBPM noise = 0.25 mm,
sCorr noise = 10 nrad

27. Current efforts of the TLS FOFB System
BPM electronics migrate to Libera Brilliance successful on August 11 and 25, 2008.
Diagnostics node implementation to capture 10 kHz rate data up to 10 seconds is underway.
Horizontal corrector power supplies replacement in October 2008.
Vertical plane is already replaced in January 2007.
Power supply noise hunting and removing => remove orbit noise > 60 Hz.
Migrate from OFB to FOFB during November ~ December 2008.
Step-by-step, without interrupt user service!
Orbit feedback performance improvement during January ~ March 2008 (before two and half months long shutdown)
Fast IDs operation
Improve orbit stability
Feedback system modeling
System modeling, quadrupole motion, power supply noise, BPM performance, control rules
Application development for the operation of the new BPM system.
Possible XBPM integration with control system to do various test as well as feedback system.
BPM electronics and communication protocol study.
New power supply control interface study, computation engine study, system latency time study.
Algorithm development (PID vs. advanced control rules).
How to survive of the FOFB system for single BPM failure.
How to reduced effects from small random noise? (weighting the singular value by using Tikhonov regularization method, reduced bandwidth for the small singular values channels, …)

28. XBPM Test – BL10 XBPM Y Similar behavior ON Orbit Feedback OFF ON
Injection
Injection
Similar behavior ON
Orbit Feedback OFF ON
~ 0.2%
Update rate: 10 Hz
Keithley 2701 DMM, 3 PLC
60 Hz and 120 Hz components is filted.
Current OFB loop use the existed feedback parameters after BPM upgrade.
FOFB will commissioning during November ~ December 2008.
Fine tune and improvement will be done in 2009.

29. How to Modify the TLS FOFB System as the TPS FOFB Testbed?
Approaches:
Modify the TLS fast orbit feedback system step-by-step
- Without interrupt the operation of TLS
- Need not extra manpower
- Develop corrector power supply (MCOR crate) new control interface ?
Control system access via an Ethernet port
Dedicated fast setting port, GbE (UDP/IP) or Rocket I/O?
Topics will study:
Computation engine study – aTCA crate system
How to share fast orbit data among processors
(Share memory or another approach?)
System latency time design
Control algorithms (PID and advanced) development
Modeling exercise
Performance estimation
BPM electronics and communication protocol study
BPM links reliability study
XBPM interface study
Reliability study
Fault tolerance algorithms study
Most important - Manpower training

30. And Build in Diagnostics
Proposed Infrastructure for the TLS FOFB Migrate to as testbed for TPS Project
TLS
Control System
Control Network
AdvancedTCA Crate,
with
Switch Blades,
Compute Blades,
And Build in Diagnostics
MontaVista Linux
Centralized or Distributed computation can be decided later!
Full function control access at slow rate
GbE Fiber Link
(Setting Only)
MCOR PS &
Controller,
Concentrator #2
MCOR PS &
Controller,
Concentrator #N
MCOR PS &
Controller,
Concentrator #1
GbE Fiber Link
(for Diagnostics)
Corr
Corr
Corr
Corr
Corr
Corr
10 kHz rate interface
GbE Fiber Link
(for FOFB)
Corr
Corr
Corr
Multi-Gigabits Links
BPM Electronics 1
BPM Electronics 2
BPM Electronics n
R6 BPM
BPM Electronics 1
BPM Electronics 2
BPM Electronics n
R1 BPM
BPM Electronics 1
BPM Electronics 2
BPM Electronics n
R2 BPM
TLS Ring ?
XBPM
XBPM
XBPM

31. Orbit Feedback System Planning for the TPS

32. Outlines
Stability Requirements
Performance Simulation
Bandwidth Requirement
Hardware components
(BPM/XBPM, Corrector/PS, Vacuum Chamber)
SOFB vs. FOFB - Strategy
Current Efforts
Summary

33. Stability Requirements of the TPS
Beam size x,y and beam divergence x’,y’ for 1 % coupling, 24P79H2 configuration. Natural horizontal emittance is 1.6 nm-rad.
Source point
σx (μm)
σx’ (μrad)
σy (μm)
σy’ (μrad)
12 m straight center
165.10
12.49
9.85
1.63
7 m straight center
120.81
17.26
5.11
3.14
Dipole (1 degree source point)
39.73
76.11
15.81
1.11
Rules of thumbs for vertical orbit stability:
y/10 : ~ 0.5 mm stability is required! or
y/20 : ~ 0.25 mm stability is required!
Reference:
1. Paragraph of “Accelerator” in the TPS Design Handbook, in preparation phase.
2. Robert Hettel, “Beam Orbit Stability”, SRI 2003 meeting.

34. Vertical Corrector Power Supply Noise Tolerance
Orbit distortion caused by DC θi kick from corrector i
Assume βs = 5.53 (bpm at 7m straight line), βi = 9.58 (vcor mean), νy = 13.25
For uncorrelated ensemble of N correctors (N = 168) :
(rms)
(rms) contributed from correctors should be limited by:
nrad (rms)
Performance requirements of vertical corrector power supply are much more stringent than horizontal ones!!
Ref: R. Hettel, “SPEAR 3 8-Channel Power Supply Controller Performance and Functional Requirements”, Preliminary Design Review, July 2, 2001.

35. Simulation Procedures
Take simulation to verify performance requirement of power supply and BPM.
BPM noise and power supply noise will be introduced.
Real orbit position can be calculated including quad vibration and calculated corrector trim kick
BPM signal without feedback
Quad displacement
Quad strength
BPM output signal
BPM noise
BPM output signal is used to calculate the kick correction strength with feedback on.
Real beam position
Calculated trim kick correction
Power supply noise
Reference: Li-Hua Yu, “Issues on Closed Orbit Feedback for NSLSII”, PAC 2005.

36. Correction Algorithm & Response Matrix
Response matrix R relates the orbit shifts to the steering magnet changes as a linear form:
Singular value decomposition is employed to calculate pseudo-inverse of response matrix and avoid the unnecessary large strengths in correctors.
In the low frequency range, the gain of PID controller is so high that we can simplify the calculation of the correction as an equation:
Calculated trim kick correction
BPM output signal

37. P + UT W-1 V + I + - D + Orbit Feedback Loop Simulation
Power Supply Noise
Reference Orbit P
fc = 2 kHz + UT
W-1 V
Power Supply + I + - D
Corrector
Response Matrix R = V * W * UT
fc = 80~300 Hz
Accelerator
Vacuum
Chamber
BPM +
Measured Orbit +
BPM noise
Orbit Disturbance
due to Quadrupole Vibration
Real Orbit
fc = 80~300 Hz
Simulation Noise Conditions: squad vib = 1 mm, sBPM noise = 0.25 mm, sCorr noise = 7 nrad

38. Lump Sum All Effects Together for the Vertical Orbit Stability
Response Matrix vs. Eigenvalue
squad vib = 1 mm, sBPM noise = 0.25 mm,
sCorr noise = 7 nrad, cutoff no.=68
Horizontal plane:
maximum eigenvalue = 711.8
minimum eigenvalue = 0.322
Vertical plane:
maximum eigenvalue = 585.8
minimum eigenvalue = 0.359
Regularization might need!
Neglected small singular values with expense of reduce overall correction efficiency
Tikhonov regularization (DLS)
Reduce bandwidth for the small singular values channel (SPEAR 3)

39. Effect of SVD Cutoff No. without Bpm & Corrector Noise
squad vib = 1 mm
sBPM noise = 0.0 mm,
sCorr noise = 0 nrad
Cutoff No.=0
If SVD cutoff number greater than 68, orbit displacement will greater than around 0.3 um even after orbit feedback on.
Cutoff No.=68
Effect of SVD Cutoff No. with Bpm & Corrector Noise
Cutoff No.=0
squad vib = 1 mm
sBPM noise = 0.25 mm,
sCorr noise = 7 nrad
SVD cutoff number will depend on sensors’ precision.
Cutoff No.=68

40. Frequency Response Simulation
System’s Frequency Response
Assumption:
Corrector bandwidth = 100 Hz
PS bandwidth = 2 kHz
Vacuum Chamber bandwidth = 100 Hz,
BPM latency = 350 msec
Closed loop B.W.
~ 140 Hz
Open loop B.W.
~ 70 Hz
Closed Loop Sensitivity Function
Quad Disturbance Sensitivity Function
Sensitivity function = |1/(1+ Gtransfer function)|
Sensitivity function = gain from quad disturbance to sensor
3dB B.W. ~ 60 Hz
3 dB B.W. ~ 50 Hz

41. How Much of Closed Loop Bandwidth Needed?
Most of prominent noise is located between DC to less than 60 Hz (power line frequency), major sources come from mechanical vibration, ground motion, …etc.
Speed of ID parameters change is limited by FOFB bandwidth. => Increase FOFB bandwidth as fast as possible.
Some labs have orbit motion at line frequency and its harmonics due to power supply ripple (e.g. ELETTRA).
TPS baseline design B.W. for FOFB is 100 Hz .
(major limitation come from vacuum chamber and magnet lamination)
Various hardware limitation will be studied immediately.
Control algorithm to increase the loop bandwidth is in the track
Good power supply is very helpful!

42. BPM Block and its Electronics
Pickups Design and Fabrication (cooperate with Vacuum Group)
Small Aperture -> Sensitivity (standard BPM: 13 mm, primary BPM: 10 mm)
Optimize the sensitivity and linearity
Careful design of the BPM fixture
Primary BPM
(Racetrack 68 x 20 mm)
Standard BPM
(Elliptical 68 x 30 mm)
Kx, Ky ≈ 10 mm
Kx, Ky ≈ 13 mm
Accompany with the Vacuum Group to design the BPM block
Tentative Specification of the Storage Ring BPM Electronics
Parameters
Range
Performance
Turn-by-turn resolution
0.5 mA
< 10 mm
10 mA
~ 1 mm
Resolution (10 Hz update rate)
0.5 ~ 10 mA
< 1000 nm
80 ~ 400 mA (14 dB range)
< 200 nm
Resolution (10 KHz update rate)
80 ~ 400 mA
< 250 nm
Beam current dependence
< 1 mm
Filling pattern dependence
Libera Brilliance is the baseline design.
Intensive tests of Libera Brilliance are scheduled.
Alternative low cost and high performance solution vs. manpower requirement is under investigation.

43. Corrector Power Supply Requirements
Correctors
All correctors will be a back-winding on the sextupoles – current planned.
Current plan for the sextupole magnets:
~ 0.5 mm thick lamination is persured, low carbon steel.
> 300 Hz in B.W. is expected.
Corrector Power Supply Requirements
168+ horizontal and 168+ vertical correctors.
Power supply small signal bandwidth > 1 KHz
Can corrector + vacuum chamber bandwidth > 100 Hz ?
100 Hz closed-loop BW is the baseline design,
Is > 100 Hz closed-loop BW achievable?
Kick resolution should be less than the estimated noise level
=> allowed maximum noise ~ 10 nrad rms
=> at least 18 bits ENOB (if 0.7 mrad full scale)
Assume corrector: Lcoil ~ 15 mH, Rcoil ~ 1.5 W, Rcable ~ 2.5 W, PS: Vmax ~ 50 V, maximum AC kick angle:
@ 60 Hz, qmax ≈ 120 mrad ( without count eddy current loss)
@ 100 Hz, qmax ≈ 70 mrad (without count eddy current loss)
Assume Imax=10Amp

44. Eddy Current Losses in the Vacuum Chamber
Vacuum chamber at sextupole (corrector): Ti-bellows with interior CuBe RF contact shielding is the current proposal.
Problems need further study: if the bellows does not cover full length of the magnet, will any effect happen?
Bending chambers with S-magnets, three for each cell, the chamber wall inside the S-magnets will be machined down to a thickness of 1.5 mm and left a clearance of 1.6 mm in between,
Problems need further study: The eddy current effect of this complicated shape.
Computation and measurement is in planning to confirm everything no problem!
Extra dedicated fast correctors (2~4) per cell (Glenn’s suggestion)

45. Issues Related to the TPS orbit feedback system should be Addressed
BPM design
Button size
Button heating
BPM calibration
Corrector/ vacuum chamber interface
No separate fast corrector => Right strategy?
Slow and fast correction function embedded at the same magnet
Power supply
TBD
Control system interface

46. Conceptual Design of the TPS Orbit Feedback System
BPM
Libera Brilliance (10 kHz update rate, ~ 2 kHz BW)
XBPM interface (fiber link) - > 2 kHz real-time data acquisition (> 300 Hz BW)
Orbit measurement
Slow orbit measurement > 10 time/sec to control servers/consoles.
Fast orbit acquisition for feedback purpose
~ 10 kS/sec, sync by event system.
Share orbit information among feedback processor via a dedicated fibre link
Block data capture is included for diagnostic purposes
Corrector control
Digital power supply is preferred for feedback corrector control
GbE interface for fast corrector setting by UDP broadcasting
~ 10 k update/sec
> 18 bit control resolution (20 bits is preferred)
Historical recording is included for diagnostic purposes
Feedback Processor and Algorithm
Feedback engine + RTOS (Linux Real-time patch or MontaVista Linux)
Various control rules can be chosen
Slow orbit feedback => running at control console (LabCA+Matlab)
Fast orbit feedback => dedicated feedback system
Corrector maximum steered angle :
~ 0.7 mrad (< 10 Hz)
~ Hz

47. Slow Orbit Feedback System
Run at EPICS control consoles
LabCA will interface EPICS to Matlab environment.
168 BPM + 2 Corrector EPICS IOC (to control 48 power supply controllers)
Each power supply controller can control 8 or 16 corrector power supplies.
10 Hz updated rate – sampling rate of the SOFB.
TPS has no dedicated fast correctors therefore the corrector power supplies controllers will be designed to be able to accept both of slow and fast settings.
Fast Orbit Feedback System
Include BPM data acquisition, corrector PS setting, feedback computation engine processors.
All of BPM data should be shared to compute corrections while each of PS corrections can be calculated separately. Centralized or distributed infrastructure will be determined by CPUs, network & power supply control interface performance.
Adopt timing systems to synchronize different processors.
10 kHz updated rate.
Single Fast + Slow Orbit Feedback System
Combine Slow and Fast OFB as a single system. Need further study!

48. build in Diagnostics to capture fast data Path length compensation
Proposed Infrastructure for the TPS Orbit Feedback
AdvancedTCA Crate,
with Switch Blades,
Compute Blades,
build in Diagnostics to capture fast data
TPS
Control System
Control Network
Path length compensation
GbE Fiber Link Or
Rocket I/O Link
(Setting Only)
Master Clock
Full function control access at slow rate
On-line modeling
computer
PS controller #1
PS controller #2
PS controller #M
GbE Fiber Link Or
Rocket I/O Link
(Read Only)
Power supply
PS 2
PS 1
PS N
PS N
PS 1
PS 2
PS 2
XBPM
PS 1
10 kHz rate interface
PS N
XBPM
TPS Ring
BPM Electronics 1
BPM Electronics 2
BPM Electronics n
BPM Group 1
BPM Electronics 1
BPM Electronics 2
BPM Electronics n
BPM Group 2
BPM Electronics 1
BPM Electronics 2
BPM Electronics n
BPM Group N
N: number of BPM grouping
4, 6, 12 ?
XBPM
XBPM
XBPM
XBPM

49. How to send BPM fast data to computation engine?
1. BPM Grouping (working with vendor now)
Main Link
(To Fast Orbit Feedback System)
Uni-direction GigE (UDP Package for one group data)
Redundancy Link
(To Fast Orbit Feedback System)
Rocket I/O data stream (one group data)
Slave
Slave
Master
Slave
Libera Grouping (1 ~ 16 units or 64 units?)
Multi-gigabits bidirectional links
FOFB communication:
Grouping scheme (8 ~ 64 BPM +XBPM ?)
Grouping latency < 30 msec
Primary BPM
(Racetrack
68 x 20 mm)
Standard BPM
(Elliptical
68 x 30 mm)
2. Alternative solution is in study also.
(discuss with possible vendor on the way, it can be implemented on the TLS BPM system for various tests)
DLS (very similar with Libera Grouping), Soelil, Petra III, or another new kind solution?

50. IOC How about turn-by-turn (bunch-by-bunch)? FPGA + XBPM ADC range
How to Connected of XBPM to Control System and Feedback System?
Multi-channel electrometer (w or w/o biased)
DL Model (APS, TLS, …)
LoCuM-4 (BESSY II, SLS, TLS, …)
FMB OxFord I400 (…)
CEAN AH401 (ELETTRA, …)
Many in-house design
or New design (integrated solution)?
Goal: Share data by accelerator control system and Beamline control system via EPICS CA mechanism
How about turn-by-turn (bunch-by-bunch)?
Machine
Control System, ~ 10 Hz rate
FPGA +
ADC
range
control
(Embedded
EPICS ?)
IOC
Multi-channel
signal conditionings
(with bias option)
XBPM
Beamline Control System
Ethernet or
XBPM
(option)
Rocket I/O or GbE (UTP/IP) interface to feedback system Io
Inject data into BPM grouping?
1 kHz ~ 10 kHz rate ?
Orbit spectrum analysis
Feedback
Discuss with possible vendor on the way, several Light Sources have similar concepts! e.g. Libera Photon? …

51. How to Send Correction Command to Fast Corrector Power Supply?
Power supply controller can interface 8 or 16 power supply
Via Gigabit Ethernet or Rocket I/O interface
All fast corrector power supply controller is connected to the computation node via fiber, as similar as the BPM grouping
=> The computation nodes can be installed at one 19” rack
Proposed Feedback Engine Layout (Baseline design)
AdvancedTCA (aTCA) crate
Switch blades
Compute blades
Feedback processors
Diagnostic processor
Links to the modeling and simulation computer
BPM data sharing by all compute blades
Backplane multi-gigabit links or Reflective memory (simple!)
Communication with BPM/XBPM (grouping to reduce communication overhead)
GigE or Rocket I/O links
Communication with corrector power supply

52. Strategy to deal with SOFB and FOFB
SOFB at beginning, then FOFB later, running FOFB only!
SOFB and FOFB running as two independent system with frequency dead-band S O F B
Corrector and vacuum chamber strategy need further study.
It is planned to test various configuration at TLS in 2009.
FOFB
FOFB run from DC, a slow system receives the fast correctors from their DC part to prevent saturation.
FOFB
Orbit feedback system with combined fast and slow correctors (similar as NSLS-II proposed system)
Slow control rules
Accelerator
Response
Slow corrector
BPMs
Fast control rules
Accelerator
Response
Fast corrector
Golden Orbit

53. Accompany with efforts of TLS FOFB upgrade
Current Efforts for TPS Orbit Feedback
BPM, corrector, vacuum chamber design
Corporation with Magnet group, Vacuum group, consult with many experts.
Two options for corrector power supply control interface are considered:
Option A: Analogue type power supply
Support analogue type power supply
FPGA module to communicate with 8 or 16 PS
DAC: 20 bits DAC, 24 bits ADC
Control system interface: Gigabit Ethernet
FOFB interface: Rocket I/O or Gigabit Ethernet
Option B: PSI/SLS type digital power supply
Dataconcentrator DPC_DC design
FOFB interface: Rocket I/O
BPM electronics and communication protocol study
Topology of the infrastructure study
Possible integrated BPM and XBPM interface study
Computation engine study and prototyping - Distributed computation scheme study
Detailed system latency time and jitter measurement
Algorithms development
Modeling study – setup a database for various components
Exercise various skills and manpower training
Accompany with efforts of TLS FOFB upgrade

54. Summary
Study of all orbit feedback related issues are on-going.
Various simulations are performed.
Limitation of all hardware components will be studied carefully.
=> Close cooperate with Vacuum Group, Magnet Group to delivery a better strategic and environment for orbit feedback.
Long-term study planning for the FOFB infrastructure is underway for following items:
Computation engines
Communication between BPM and computation engine
Communication between corrector power supplies
Upgrade project for the TLS FOFB provides a good testbed to do various studies!

55. Thank You for Your Attention!