3rd International Workshop on Beam Orbit Stabilization - IWBS2004December 6-10, 2004

Hotel Kirchbühl, Grindelwald, SWITZERLAND

Orbit Stabilizationat

Taiwan Light Source

Kuo-Tung Hsu

December 6, 2004

NSRRC Accelerator

Storage Ring(1.51 GeV)

Booster Ring(1.51 GeV)

LINAC

Transport Line

Bending Magnet

Quadrupole Magnet

Pulsed Injection Magnet

Sextupole Magnet

SRF Cavity

Insertion Device

BM2

BM1

W20 (1.8 T)

U9 (1.25 T)

SWLS (6 T)

EPU5.6 U5 SRF Cavity(Dec. 2004) SW6 (3.2T)

IASW6 (3.5 T) x 3 sets

December 20044 Conventional IDs

2 Superconducting IDs22 Beamlines

56 End-stations

Lattice type Combined function Triple Bend Achromat (TBA)Operational energy 1.5 GeVCircumference 120 mRF frequency 499.654 MHzHarmonic number 200Natural beam emittance 25.6 nm-radNatural energy spread 0.075%Momentum compaction factor 0.00678Damping time Horizontal 6.959 ms Vertical 9.372 ms Longitudinal 5.668 msBetatron tunes horizontal/vertical 7.18/4.13Natural chromaticities Horizontal -15.292

Vertical -7.868Synchrotron tune 1.06*10-2 (SRF, 1.52*10-2)Bunch length 9.2 mm (Doris Cavities, 800 kV)

6.5 mm (SRF, 1.6 MV)Radiation loss per turn (dipole) 128 keVNominal stored current (multibunch) 200 mA (~2004), 300~400 mA (2005~)Number of stored electrons (multibunch) 5*1011 (SRF cavity, 1012)

Major Parameters of the Storage Ring

Efforts to Improve Beam Stability

Coupled-bunch instability :

RF gap voltage modulation (~ October 2004)

Superconducting RF (December 2004 ~)

(to accompany double the stored beam current).

Coupled bunch feedback system

Orbital stability:

Source Elimination

Ambient temperature, Water temperature,

Enhance data acquisition system, Vibration

elimination, Power quality improvement ,

Power supply improvement …etc.

Orbit feedback system

Top-up injection

4. Vibration

6. Control System

5. Sensors Implementation

3. Thermal-Mechanical Effects

2. Heat Source Stabilization

1. Utility Capacity Improvement

<± 0.1 ℃<1 μm rms

<0.3%

<± 0.1 ℃(drift<5μm)

~± 0.15 ℃<3μm rms

~0.5%

<± 0.2 ℃(drift~20μm)

~± 0.25 ℃>± 1 ℃(drift>50μm)

>1%

Performance, ΔT

orbit

ΔIo/Io

2002 20012000199919981997

Utility building #2 constructionCHW capacity improved

CTW, CHWStability

Injector energy upgradefull energy injection

EPU air temp.U5 air temp.

SCADA implementationelectrical sensors

Water control system upgradeVF controller implementation

Utility data archive system

AHU controller upgradeAHUs reorganized

Air temp. sensors Position sensors

Global effect studies(air/water temp., cable heat)

Girder, thermal insulator , vacuum chamber, SR heat mask

BL-, RF-DIW temp.

AHU, crane vibration pre-reduced Damping study Floor meas.

Piping improv.

Program initiation

Power supply heating

ΔI monitor

Mechanical Related Source Elimination

(2003)~ 0.06%

(J. R. Chen, et. al.)

Magnet (Water Temperature)

100 200 300 40022

24

26

28

Mag-Water Temp. Beam Position

Time(min.)

Tem

pera

ture

(¢J)

0.22

0.23

0.24

0.25

0.26

Posi

tion

(mm

)

Caused by the temperature fluctuations of magnet cooling waterMagnet deformed ~ 10μm/ ℃Induced beam orbit drift: 5 ~ 50 μm / ℃

Current statusCooling water temp.: ~ ± 0.1℃

Girder Displacement

• Main cause: air temperatureSensitivity to air temp.: ~10 μm / ℃Induced beam orbit drift: 20-100 μm / ℃

• Current status: < ± 0.1 μm per 8 hr shift Air temp. : < ± 0.1℃(utility control system improved) Thermal insulator jacket

-200 0 200 400 600 800 1000 1200 14000.92

0.94

0.96

0.98

1.00

-200 0 200 400 600 800 1000 1200 140024.0

24.5

25.0

25.5

26.0

Beam Position

mm

min

Air TemperatureD

eg

ree

(C

)

0 25 50 75 10024

25

26

27

28

Dis

plac

emen

t (£g

m)

Tunnel Air Temp. Girder Disp. Outer Girder Disp. Inner

Time (Hours)

Tem

pera

ture

(¢J)

-20

-15

-10

-5

0

Expansion of Vacuum Chamber

• Caused by synchrotron light irradiation. Sensitivity to water temp.: ~ 10 μm / ℃

Move the girder (~ 0.3μm/ ) and BPM (~ 1℃ μm/ )℃ Induced beam orbit drift: ~10-30 μm / ℃

• Current statusVacuum cooling water temp.: ~ ± 0.5℃

0 6 12 18 2419.5

20.0

20.5

21.0

21.5 Girder Displacement Beam Current

Time (Hours)

Dis

plac

emen

t (£g

m)

0

100

200

Bea

m C

urre

nt (m

A)

0 200 400 600 800 1000 1200 1400-0.08-0.06-0.04-0.02

0 200 400 600 800 1000 1200 14000.51.01.52.0

0 200 400 600 800 1000 1200 14002425262728

0 200 400 600 800 1000 1200 14000

100200

Beam Position

mm

min

BPM Displacement

um

Vac-chamber Temp

Tem

p (

C)

Beam Current

mA

Power Supply Related High Frequency Orbital Noise(Source Elimination)

@ 136 mA (August 22, 2001)

Beam Spectrum Observation

High Frequency Corrector Power Supply Noise

0 100 200 300 400 500 600 700 80010

-7

10-6

10-5

10-4

10-3

10-2

Frequency ( Hz )

Ou

tpu

t c

urr

en

t ri

pp

le

( a

mp

ere

)

0 0.5 1 1.5 2 2.5

x 104

10-7

10-6

10-5

10-4

10-3

10-2

Frequency ( Hz )

Ou

tpu

t c

urr

en

t ri

pp

le

( a

mp

ere

)

Typical Corrector Spectrum

0 100 200 300 400 500 600 700 80010

-7

10-6

10-5

10-4

10-3

10-2

Frequency ( Hz )

Ou

tpu

t c

urr

en

t ri

pp

le

( a

mp

ere

)

0 0.5 1 1.5 2 2.5

x 104

10-7

10-6

10-5

10-4

10-3

10-2

Frequency ( Hz )

Ou

tpu

t c

urr

en

t ri

pp

le

( a

mp

ere

)Before Improve

After Improve

(K.B. Liu et al.)

BeforeImprove

RMS=0.03%

RMS=0.16%

Mar.08,2002186mA

June 13, 2002185mA

Observation at Infrared Beamline

AfterImprove

BeforeImprove

AfterImprove

(Y. C. LO, et al.)

Software Environment for BPM Data Access

Closed Orbit Server

Static Database Dynamic Database(Slow Orbit, 10 update/sec)

Device ControlService ProgramStatic Database Service Program

Data UpdateService Program

DatabaseLoggingProgram

Real-TimeTrend Display

LabVIEWInterface

MatlabMEX

Interface

MX-BPM Hardware

Control Ethernet

SoftwareComponents

OnControl Consoles

BPMVMEsCrates

(PPC/LynxOS)

ConsolesComputers(Compaq WS/Unix)

(PC/Linux)

Self-ConfigurationTable

Data Acquisition

Reflective Memory

(RM)Fast Orbit, 1 K update/sec

Machine ParametersService Routines

Machine Modeling(MPAP,APAP)Control Applications

Data Access Routines

Data Access Routines

April 2003

MatlabScripts

AP

MATLAB

LabVIEWVI

LabVIEW

System StatusDisplay

Alarm CheckingProgram

Parameter PageProgramData Logging

& ArchivingHardware DiagnosticsProgram

AP

Turn-by-Turn Server Program

Closed Orbit Data

Reflective Memory

(RM)Fast Orbit, 1 K

update/sec

DBPM Hardware, LR-BPM Hardware

Mode Control BPM Data

Control Program

Toother

DBPMnodes

ClosedOrbit

Server+

MX-BPMData

Acquisition

DBPMLR-BPM

DataAcquisition

Node

Turn-by-TurnData Access

Environment of BPM System

Orbit Feedback System Architecture

ControlNetwork

ControlConsoles

PC/Linux

VME

HOST

16BitDAC

RM/DMA

Private Ethernet Switch

Reflective MemoryHub

Keithley 2701PBPM Front-end

Keithley 2701 PBPM Front-end

FeedbackVMECrate

Corrector ControlVME CrateOrbit Acquisition

VME Crates

RM/DMA

16BitDAC

16BitDAC

Electron BPM(MX-BPM & DBPM) Correction Magnet Power Supply

Photon BPM

VME

HOST

RM/DMA

16BitADC

16BitADC

16BitADC

Tim

ing G

enerator

VM

E H

ostPow

erPC 7410

RM/DMA

VME

HOST

Feedback Data Capturer

VME Crate

VM

E H

ostPow

erPC 7410

PC/WindowsWS/UnixWS/Unix

Local RAM Disk

VME

HOST

RM/DMA

16BitADC

16BitADC

Tim

ing G

enerator

16BitADC

Fiber Interface

Orbit Feedback System Summary* 22 correctors + 30 BPMs for both plane* Using measured response matrix* Singular Value Decomposition (SVD) approach to invert the response

matrix* Proportional, Integral and Derivative (PID) control algorithm* Orbit acquisition rate 1 kHz* Loop bandwidth is about 5 Hz now (30 Hz before December 2003)* Unified system for global feedback and local feedback system* Remote enable/disable of the feedback loop* Orbit excursion reduced to less than ~ um level for ID operation

- U5, U9 and EPU5.6* Suppress orbit leakage due to non-ideal dynamic local bump

- EPBM* Prototype local feedback loop by using e-BPMs

Orbit Feedback System Summary (cont.)* DSP feedback engine was replaced by general purpose PPC moduleUser friendly development environmentLift maintenance difficultsSlightly increase jitter < 50 sec (DSP < 10 sec)

* Robustness enhancement of the feedback loop

BPM Check

RMS, data change rate, …etc

Limited correct setting range

Problems and Plan of the Orbit Feedback SystemMajor Problems : * Loop bandwidth is too small right now

=> cannot eliminate mechanical related oscillation

=> Limited gap/phase changing speed of IDs

Short-term Plans: * Increase sampling rate o 2 kHz to 4 kHz * Modify corrector power supply regulation loop * Increase loop bandwidth > 100 Hz

Closed Orbit : ~10 m rms with DC correction schemes. (P

eace Chang et al.)

Orbit distortions: < 10 m rms during insertion gap scan c

an be compensated for using look-up correction tables. (Pe

ace Chang et al.)

Beam orbit stability: a few m level (peak-to-peak) with a gl

obal feedback system. (C. H. Kuo et al.)

Closed Orbit and Orbit StabilityClosed Orbit and Orbit Stability

e-

Power Supply

#1

Power Supply

#2

Power Supply

#4

Power Supply

#3

EPBM Model Enable

Bump Amplitude

Control (0-5 V)

Bump Coefficient

(± 10 V)

Block Diagram of Control Electronics for

Elliptical Polarization from Bending Magnet (EPBM) ProjectDRAFT

Ratio Amplifier

x 4#1 #4#3#2

BM2 Bending MagnetEPBM VC #1

EPBM VC #2

EPBM VC #3

EPBM VC #4

EPBM Control Electronics

SYNC to Experimental

Station

Clock Generator

12 12

Corrector Strength

ILC12ILC03

#1 #2 #3 #4#1 #2 #3 #4

Line Driver x 2

EPROM

12 Bits Counter

t1

t2

t2 : user specify

Ratio Amplifier

Instrumentation Amplifier x 812 Bits DAC

++ + +

t1 : 40 msec

Polarization Control

EPBM Mode

Request

EPBM Model Request

EPBM Mode Enable

3.4o

1220 mm460 mm 375 mm 540 mm 345 mm

325 mm 135 mm 170 mm 175 mm

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0 5 10 15 20 25 30 35 40 45 50

Ver

tical

Pos

ition

(m

m)

BPM Index

Difference Orbit - EPBM 'on', DGFB 'off'

"ep0925f.dat"

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0 5 10 15 20 25 30 35 40 45 50

Ver

tical

Pos

ition

(m

m)

BPM Index

Difference Orbit - EPBM 'on', DGFB 'on'

"ep0925g.dat"

* EPBM dynamic bump with feedback

EPBM flip bump without feedback

Eliminated Orbit Leakage for EPBM Operation

(C.H. Kuo et. al.)

Insertion Devices in the TLS Storage RingInsertion Devices in the TLS Storage Ring

Insertion Device SWLS EPU5.6 U5 SW6 W20 U9 IASW

Location Section S1 S2 S3 S4/RF S5 S6 Arc 2,4,6

Type SC Pure Hyb. SC Hyb. Hyb. SC

Magnet Length (M) 0.835 3.9 3.9 1.404 3.0 4.5 0.85

Period Length λ (cm) 25 5.6 5 6 20 9 6

(Min.) Gap (mm) 55 18 18 18 22 18 18.5

Number of Periods 1.5 66 76 16 13 48 7.5

Maximum By (Bx) Field (Tesla)

6 0.67 (0.45)

0.64 3.2 1.8 1.25 3.5

Photon Energy (eV)

[Used Range]

Min. 4000 80 60 5000 800 5 5000

Max. 38000 1400 1500 14000 15000 100 14000

Defection Parameter Ky (Kx)

190.5 3.52(2.37)

2.99 17.9 33 10.46 19.6

Vertical Tune Shift Δν Vertical Tune Shift Δν (Horizontal Tune Shift)(Horizontal Tune Shift)

0.05040.0504(-0.014)(-0.014)

0.0110.011(-0.012)(-0.012)

0.0080.008 0.0360.036 0.0360.036 0.0330.033 0.050.05

Installation Date Apr.2002

Sep.1999

Mar.1997

Dec.2003

Dec.1994

Apr.1999

2005 The photon flux vs. photon energy of bending magnets and IDs at TLS. Two Taiwan beamlines, SP8-BM and SP8-U3.2, at Spring 8 are also depicted

withFeed-forward

TuneCorrection

withoutFeed-forward

TuneCorrection

Orbit stability of the NSRRC Storage RingOrbit stability of the NSRRC Storage Ring

With the follow-gap look-up table and global orbit feedback system, the orbit drift of the field scan of U5, U9 and EPU5.6 can be reduced from a few hundred microns to a few microns. When the gaps of U5, U9 and EPU5.6 are scanned from 19, 21, and 21 mm to 39, 41, and 41 mm, the closed orbit distortions indicated by the R4BPM5X (blue) and R3BPM3Y (green), those are used in the faster orbit feedback system, are within 2 microns in both horizontal and vertical planes.

(Peace Chang, et. al.)

Photon Beam Stability Monitor (Io / Io)

BM3

BM3

VFM

VFM

50 um pinhole

Sensitive toBeam size instabilityOrbit instabilityEnergy instability

Signpost of overall beam stability form users’ viewpoints

Demagnification factor : 3

PhotoDiode

Thermal Deformation

Backlash

Driver Mechanism(Optimization)

Electron Beam Stability(Transverse,Longitudinal,Beamsize, …)

History of the Photon Beam Stability (I0/I0)

May Jan Jan Jan2001 2002 2003 2004

0

20

40

60

80

100

Ach

ieve

d P

erce

nta

ge

in U

ser

Tim

e

< 1 % <0.5 % < 0.3 % < 0.2 % < 0.1 % < 0.05 %

long shutdown long shutdown

Improve cavity temperature control at 30% user time

U5, U9, EPU dynamic tuning at 100% user time

Relax U5, U9, EPU dynamic tuning speed

(K.K. Lin et. al.)

1130 1140 1150 1160 1170 1180 1190 1200197

198

199

200

201

202

203

Time (min.)

Sto

red

Beam

Cu

rren

t (m

A)

-15

-10

-5

0

5

Orb

it C

han

ge (

mic

ron

)

Date: Dec. 31, 2002 Top-up mode Test

R4BPM5X (blue line)

*Orbit change referred to the data at 1130 minute is taken with 10 Hz sampling rate.

R3BPM3Y (red line)

Stored beam current *Injection threshold current is 198 mA

Top-up injection scheme planned. Feasibility demonstrated.

(G.H. Luo et. al.)

Top-up Injection ProjectTop-up Injection Project

Experiment of Top-up injection

Filling pattern at the beginning of top-up injection

Filling pattern at the end of top-up injection

User’s shift decay mode Test of top-up mode

Zoom in, injection interval 2 min.

(G.H. Luo et. al.)

Cooling Water and Chamber Temperature

Outlet cooling water temperature

Chamber’s temperature

Top-up test run

(G.H. Luo et. al.)

Compound Displacement of the of Beam Position Monitor Reading

Stored beam current in mA

R1 BPM3 X-displacement in m

R1 BPM3 Y-displacement in m

x ~15 m

y ~5 m

-Intensity dependency of BPM electronic and BPM support fixtures (~ m)-Filling pattern dependency of BPM electronics (~ m)-RF gap voltage condition variation-BPM support structure (~ 10 m)-Thermal related (~ 10 m)

Top-up test run

(G.H. Luo et. al.)

R1BPM1Y

R2BPM7Y

R6BPM4Y

Vertical Beam Position Variation

20 m

20 m

20 m

Top-up test run

R1BPM1X

R4BPM3X

R3BPM8X

Horizontal Beam Position Variation

20 m

9 m

5 m

Top-up test run

Renew 1.5 sec half-since injection kicker to reduced jitter and to improve waveform matching .

Gate of the orbit feedback loop is a provincial solution to remedy mismatching problem of the injection kickers.

User experiment with injection gate and without is performed, acceptable results get up to now.

Improve gun pulser and linac performance to improve filling pattern control.

Studies of the injector reliability, injection efficiency, and minimization of orbit perturbation during injection, etc., are ongoing.

Top-up operation is scheduled in late 2005.

Top-up Injection PlanTop-up Injection Plan

Electron Energy 3 ~ 3.3 GeV

Current 400 mA at 3 GeV or 300 mA at 3.2 GeV (Top-up injection)

SR Circumference 518.4 m (h = 864 = 25·33 , dia.= 165.0 m)

BR Circumference 499.2 m (h = 832 = 26·13, dia.= 158.9 m)

Lattice 24-cell DBA

Straight-section 10.5 m x 6 ( σv = 10.5 μm, σh = 160 μm) 6 m x 18 ( σv = 8 μm, σh = 110 μm) 3 m x 12 ( σv = 4.5 μm, σh = 250 μm; In-achromat)

Bending-section x 12

Emittance < 2 nm·rad at 3 GeV (Distributed dispersion)

Coupling 1 %

RF Frequency 500 MHz

RF Max. Voltage 4.8 MV (4 SRF cavities)

RF Max. Power 720 kW (4 SRF cavities)

Site NSRRC in Hsinchu Science Park , Taiwan

Building 223 m OD (700 m circumference) 139 m ID (437 m circumference)

Parameters of the Proposed Taiwan Photon Source

Sub-m orbital performance is one of a design goal.

Summary

* To achieve m (sub-m) orbital performance is a short term goal at TLS.* Further develop of fast orbit feedback system is needed in following area:

• Corrector PS improvement• High sampling rate (~ 2 KHz/4 KHz)• PS control interface• BPM system improvement in engineering as well as software functionality.

* Top-up operation mode is scheduled, beam orbit stability will be improve further.* Sub-m orbital performance is one of a challenge for the newly proposed 3 ~ 3.3 GeV Taiwan Photon Source