Proceedings of IBIC2012, Tsukuba, Japan

TUPA17TPS BPM ELECTRONICS PERFORMANCE MEASUREMENT AND
STATISTICS
P. C. Chiu, K. H. Hu, C. H. Kuo, K. T. Hsu
NSRRC, Hsinchu 30076, Taiwan

The BPM electronics Libera Brilliance+ are developedfor Taiwan Photon Source (TPS) which is a 3 GeV
synchrotron light source constructed at NSRRC. ThisBPM electronics can accommodate four BPM modules
with integrated FPGA-based hardware. The BPM wascontracted in the 2nd quarter of 2011; I-Tech award thecontract to provide BPM electronics for the TPS project.
The first prototype had been delivered in August 2011and performed the preliminary test to verify fundamental
specifications; the rest units had been delivered
respectively in December 2011 and June 2012. The
acceptance test for all units had been completed during
June to August of 2012. Performance of each unit areindividually tested and measured. Statistics data will besummarized in this report.

INTRODUCTION
The TPS is a state-of-the-art synchrotron radiation
facility featuring ultra-high photon brightness withextremely low emittance [1]. Civil constructions areexpected to be finished in early 2013. Machinecommissioning is scheduled in 2014. The TPS accelerator
complex consists of a 150 MeV S-band linac, linac tobooster transfer line (LTB), 0.15–3 GeV booster
synchrotron, booster to storage ring transfer line (BTS),
and 3 GeV storage ring. The storage ring has 24 DBA
lattices cells with 6-fold symmetry configuration. Thissynchrotron machine requires beam position stability lessthan 1/10 beam size therefore the position measurement
system is also required to achieve one hundred or eventens of nanometer resolution. TPS has decided to adoptLibera Brilliance+ [2] electronics for the position
measurement. The new instrumentation has thesatisfactory performance and diagnostic functionalities aswell as provides interface for fast orbit feedback
application [3]. The vast tests including current
dependency, filling pattern dependency, temperaturedependency, latency estimation, long-terrn and short-term
stability have been done and summarized in this report.
Statistics data will be summarized.

BPM SPEC AND FUNCTIONALITESThe TPS storage ring is divided into 24 cells and there
are 7 BPMs per cell; the booster ring has six cells where
each cell is equipped with 10 BPMs. The number of BPM
modules installed in the BPM platform might vary due tovarious install consideration and future expansion.

Therefore, the BPM platform is designed to accommodate
maximum 4 BPM modules. The TPS acquire 76 BPM
platforms in MicroTCA based form factor and 228 BPM
processors modules for storage ring and booster
synchrotron application exclude the spares or the extra
BPM due to the later design change.
The conceptual functional block diagram of the BPM
is shown in Fig. 1. It will be embedded with EPICS
interface for control, monitor and configuration. Thetiming AMC module would provide functionalities ofsynchronization, trigger, interlock and post-mortem. The
BPM platform should also accommodate the FPGA
module for fast feedback application for the future
expansion.
BPM Module #1
RF front-end

PCI Express (AMC.1)
LVDS links
LVDS links ?

ADC FPGACOM Express(Linux + EPICS, ..etc.)

GigE

BPM Module #2
RF front-end

ADC FPGA

BPM Module #2
RF front-end

Clock Distribution,Interlock
ModuleADC FPGA

Clock &TriggerInterlock
Extra
Digital I/O?
MGT

BPM Module #4
RF front-end

ADC FPGAGrouping(3.2 Gbit/sec?)
Data communication
Feedback FPGAGbE or 10 G (UD(GDX)
GbE orRocket I/O(Corrector Control)

Figure 1: BPM platform functional block diagram.
The major specifications that the system must be
fulfilled are also listed in Table 1.
Table 1: TPS BPM Performance Requirements
Parameters

Singlepass
sensitivity andresolution
Turn-by-turnresolution

Resolution (10Hz update rate)

Resolution (10KHz update rate)
Beamcurrent
dependence
Fillingpatterndependence
Temperaturedependence

Beam
Charge/Current Range
100 pCSpec.
(in rms)

Measured(in rms)

< 1 mm

0.2 mm

0.5 mA< 1 mm0.15 mm

10 mA< 100 um

10 um

500 mA~ 1 um1um

0.5~10 mA< 1000 nm

80 nm

100~500 mA(14 dBrange)
100~500 mA< 100 nm

20 nm

< 200 nm

100 nm100~500 mA< 1000 nm

200 nm100~500 mA< 1000 nm

200 nmo<1000 nm/ C~ 100 nm/oC

ISBN 978-3-95450-119-9
Beam Position Monitor System

1c 2012 by the respective authors — cc Creative Commons Attribution 3.0 (CC BY 3.0)
Copyright ○Abstract

TUPA17

Proceedings of IBIC2012, Tsukuba, JapanACCEPTANCE TEST & SETUP
The first BPM prototype had been delivered in August
2011; the rest units had also been delivered respectively
in December 2011 and June 2012. The delivered units had
been performed functionality and performance test toensure compliance with this specification in this August.
The test environment setup is shown as Fig. 2.
Test Items:
Resolution
Intensity dependency
Filling pattern dependency
Include camshaft mode
Short term performanceLong term drift
Position dependency
Ambient temperature dependencyϭϳϮ͘ϮϬ͘ǆǆ͘ǆǆEĞƚǁŽƌŬ
W/^/Kϭϵϭ͘ϭϲϴ͘ϮϬϮ͘ǆǆ^ǁŝƚĐŚ

R&S SMB-100A(SBM-B1H)(-145 ~ 20 dBm)

10 MHz33522A Function/ Arbitrary
Waveform Generator & P400 DDG

AmbientTemperature
Monitoring(RTD)

Long bunch-train

RF gateGappercentage
in filling
100%

Isolated bunch

MC Trig PMInterlock

EPICS Interface
The EPICS interfaces for all BPM platforms are tested.
One defect is that some waveform records are empty (datais zeros) for first acquisition even external trigger is given.
Besides, EPICS CA server crash had occasionallyoccurred and was reported to the vender. The upgrade tothe EPICS IOC is foreseen in October 2012 roughly.

Housekeeping
The BPM platform provides power supply statusmonitoring, temperature monitoring, fan statusmonitoring and fan control. The status looks good fromthe system maintenance point of view.

Simulated Beam Signal

ĞǀŝĐĞhŶĚĞƌdĞƐƚ;hdͿ4 Ways
PowerSplitter

Simulated
Beam Position

Synchronization StabilityWDƉůĂƚĨŽƌŵ
н
WDŵŽĚƵůĞ

Insert hear for latency measurement

2012.06.20

Figure 2: Set up for the acceptance test.
The BPM electronics will be sensitive to very smallchange (one part of 10000 or less) and many factors willaffect the measurement. Since the beam splitter issensitive from the ambient environment, we are using
Polyethylene foam to perform thermal isolation. The
vibration of cable will cause signal variation as well. The
fixed solid cables are also essential to achieve nano-metermeasurement performance. The setup for acceptance test
is shown in Fig. 3.

Synchronization is accomplished by internal PLL tolock to the revolution frequency and the stability isobserved for 9 modules during 60 hours. The phase errors
had never gone out of േ 1o region and the PLL had
always remained locked status.

RESOLUTION TESTThe BPM electronics provides several data flow
including around 10 Hz slow data, 10 kHz fast data, turnby turn data, and ADC raw data. These different data flow
resolutions would be estimated respectively as followings.

Slow Data
Figure 4 shows the histogram of horizontal and vertical
position resolution distibution at power level around -10
dBm for 228 BPM modules. Most of these modules could
achieve 20 nm resolution. Few mouldes could be over 50
nm which could be caused by ambient environment andwill be further explained later. Fig. 5 shows resolutionchanges versus input power level variation. It can beobserved that the resolutions don’t worsen until the power
level drops less than -50 dBm.

Figure 3: Set up for the acceptance test.
No.

The current dependency, filling pattern dependency,
temperature dependency, latency, and short-terrn andlong-term stability are verified and shown as thefollowing sections.

Resolution Histogram at Power Level = -10 dBm
200

FUNCTIONALITY TEST
To support 24/7/365 operation of the BPM electronics,
functionalities like cold start, shutdown, housing, controlsystem interface should meet the requirements.

1000All BPM platforms and BPM electronics have been
performed cold and shutdown test. Only minor problems
encounter. One platform had been re-installed and reconfigured to resolve continuous program fail. One of 228

0.04

0.06
0.08
Hor. resolution (μm)

0.1

0.12

0.02

0.04

0.06
0.08
Ver. resolution (μm)

0.1

0.12

1000

Cold Start and Shutdown

0.02

200
No.

c 2012 by the respective authors — cc Creative Commons Attribution 3.0 (CC BY 3.0)
Copyright ○modules hardware had malfunction after three months
operations. Reason of the fault is still in investigation.

Figure 4: Histogram of horizontal and vertical position
resolution distibution at power level around -10 dBm for
228 BPM modules.

ISBN 978-3-95450-119-92Beam Position Monitor System

Proceedings of IBIC2012, Tsukuba, Japan

TUPA17Fast Data
FA data resolution is around 100 nm and meets thespecification which should be less than 200 nm as well.
Fig. 7 shows the results.

50300
00-20-40-60

Hor. position(μm)

100BPM no.

Power Level

5200
1000-60

Power Level

Figure 5: Position resolution versus power level changefor 228 BPM modules.

Turn-by-turn Dataσx= 0.82418 μm

Hor. pos. (μm)

24220200400600

800

Ver. pos. (μm)

1000

σy= 1.0352 μm-40-450200400600
TBT samples

80002004001000(a) Switch and DSC Off

200400600

Ver. pos. (μm)

10800

1000

3.50200400600
Fa samples

1000

σy= 0.86458 μm

8001000

Figure 7: FA data.

BEAM CONDITIONS AND
ENVIRONMENTAL EFFECTS TESTThe BPM electronics should be not sensitive but
immune to the beam condition including beam current
dependence, filling pattern, ambient temperature,mechanical vibration and etc. Efforts are summarized inthe following paragraphs.

Current Dependency
TPS will be operated at top-up mode. Current
dependency requires within 1 um variation for 100 mA ~500 mA range. Fig. 8 shows current dependency test
result which is less than 200 nm for 40 dBm input power
level changes.

Ver. pos. change (μm)

Hor. pos. (μm)σx= 0.88 μm

15100800

σy=0.11859 μm

10-10-20-40

Power Level
20600

43

Turn-by-turn data resolution is evaluated between thetwo modes of switching and DSC (digital signalconditioning) on and off. There is no clear spike causedby analog switch input because new compensation
method has been applied in this new platform. Both of theresolution could achieve around 1000 nm which meet thespecification at 500 mA (~10 dBm). Fig. 6 shows theresults. At lower current mode of 0.5 and 10 mA whichpower level decreases around -50 and -24 dBm, theresolutions are 150 and 10 um respectively, which alsoachieve the required performance.
26

σ x=0.098977 μm

0-20-40

BPM no.

-50

1413.50300

2014.5

Ver. position(μm)σy (μm)1015-60

500100150200150200

BPM no.

10-10-20

Power Level-40-60500100
BPM no.

5Figure 8: 228 BPMs current dependencies.
00200

400
600
TBT samples(b) Switch and DSC On
Figure 6: TBT data.

800

1000

Filling Pattern Dependency
Figure 9 shows the filling pattern dependency versus
different percentage of filling width with and without
power compensation. Results clarified that both ofISBN 978-3-95450-119-9
Beam Position Monitor System3c 2012 by the respective authors — cc Creative Commons Attribution 3.0 (CC BY 3.0)
Copyright ○200

Hor. pos. change (μm)σx (μm)10

TUPA17

Proceedings of IBIC2012, Tsukuba, Japan

Without Power compensation-25.8-26-26.2-26.4-26.6
2030

40506070
Fill Width(%)

80

90100

Ver. pos.(μm)

Hor. pos.(μm)

horizontal and vertical position changes are much lessthan 100 nm and can be ignored.

30

40506070
Fill Width(%)

8090

10090100

Ambient Temperature Effects

54.8
4.6
4.4
4.2
20

Sum (Count)vertical positions stay unchanged. It could be concluded
that Camshaft mode fill pattern dependency almost can beignored either.

x 1032130

740506070
Fill Width(%)

80

To characterize drift due to ambient temperature
variation, a BPM platform was put into an incubatorchamber as Fig. 11 to do long term drift measurement.
The incubator is set in soak mode from 25 to 30 degree,
27 to 29 and 28 to 29 degree in Celsius scale respectively.
Fig. 12 shows the results of beam position changes versus
temperature and it is observed that both of horizontal andvertical position changes are smaller than 100 nm/ Ʊ C.
Horizontal position fluctuation is observed to have 3
minutes delay compared to vertical one and it is inferredcaused by thermal propagation delay on four ADCs.

With Power compensation

54.8
4.6
4.4
4.2
2030

40506070
Fill Width(%)

80

90

100

30405060
70
Fill Width(%)

80

90

100

30

40506070
Fill Width(%)

80

90

100

7Hor. Pos. (μm)

BL22HI-TP01-039 Filling pattern dependency-18.4-19-18.6
-18.8

010

2030

4050

6070

80

90

10001020304050Time (sec)

60

7080

90

170.8x 1040.81.301020304050Time (sec)60708090

tŝƚŚŝƐŽůĂƚĞĚďƵŶĐŚ

tŝƚŚŚŝŐŚĞƌŝƐŽůĂƚĞĚďƵŶĐŚ

Figure 10: Position observation at camshaft mode filling
pattern with/without isolated bunches.
The camshaft mode filling pattern is also tested as
Fig 10. There were three modes observed: (1) without
isolated bunches (2) with isolated bunches (3) with larger
isolated bunches. It can be seen that sum value increasingreflects the switch of three modes while horizontal andVer. Pos.(μm)

tŝƚŚŽƵƚŝƐŽůĂƚĞĚďƵŶĐŚ

1.2

1.4

1.6

1.8

2

1

1.2

1.4

1.6

1.8

2

25
0.811.2

1.4Time (hr)

1.6

1.8

2100

Hor. Pos. (μm)

1.2

15

17.5
17.4
17.3
17.2
17.1
2.5

3

3.5

4

4.5

3

3.5

4

4.5

3

3.5
Time (hr)

4

4.5

4.45
4.4
4.35
4.3
2.5
Sum (count)

Sum (count)

17.5

30

100

4

1.4

18

4.5

-19.2
-19.4

BL22HI-TP01-039 Temperature dependency

Hor. Pos. (μm)

Figure 9: (a) Filling pattern dependency without powercompensation. (b) With power compensation.

Ver. Pos.(μm)(b)

Figure 11: Libera Brilliance+ platform put inside anincubator which provide precision temperature control in
the range between 0~60 oC. Measurement is performed
around 30oC.

Sum(count)

x 10
32120

Sum (Count)Ver. pos.(μm)-26-26.2
-26.4
-26.6
-26.8
20

Ver. Pos.(μm)

c 2012 by the respective authors — cc Creative Commons Attribution 3.0 (CC BY 3.0)
Copyright ○Hor. pos.(μm)(a)

30282.5

ISBN 978-3-95450-119-9
4Beam Position Monitor System

Hor. Pos. (μm)

Proceedings of IBIC2012, Tsukuba, JapanLATENCY TIME

-15.2
-15.4

Ver. Pos.(μm)

0.5

11.5

2

11.5

2

1.5

25.250.5Sum(count)

TUPA1730
290.5

1Interlock output is used to measure the FA latency forevaluating fast orbit feedback application. A steep orbitchange implemented by controlled gating signal is applied
to trigger interlock. The latency time calculated by thetime difference between the input change and theinterlock output is around 150 േ 50 us as Fig. 14. 100 us
jitter is roughly equal to one FA sample period and theFA latency time is one to two FA sample period.

Time (hr)Figure 12: Temperature dependency around 100 nm/ƱC.

Long-term and short-term position stabilities arestudied as Fig. 13. Most of position drifts could be lessthan 500 nm within 30 minutes. It’s observed thatmechanic stability including fan vibration, air flow andcable sway quite effect BPM readins. In a steady andcontrolled condition, long-term position stability for 14hours and 60 hours could be much less than 1 um as Fig.
13 (b)(c).

ϭϬϬμƐĞĐ:ŝƚƚĞƌ͗ϭϬϬμƐĞĐĞĂŵWŽƐŝƚŝŽŶŚĂŶŐĞ/ŶƚĞƌůŽĐŬĐƚŝǀĞ

200

No.

150

Figure 14: The time difference between input change andinterlock output is around 150 േ 50 us.

100
500-0.500.5
1Hor. Position Drift (μm)

1.52SUMMARY

200No.

150
10050
0.5
11.5
Ver. Position Drift (μm)

22.5

BPM 1 : X

2.52

Ver. Pos. (μm)

216.4
16.2
1615.8
15.6

5.4
5.2
5
4.8
4.6

Ver. Pos. (μm)0(a)

Hor. Pos. (μm

Hor. Pos. (μm)

0-0.5468Time (hr)1012
BPM 1 : Y

2468Time (hr)1012

BPM 1 : X

102030Time (hr)40-18-18.2-18.4-18.6-18.8

50
BPM 1 : Y

102030Time (hr)

40TPS BPM electronics factory acceptance test (FAT)
had been completed in August. Each BPM platform andmodule had been individually tested and measured.
Fundamental functionalities are passed. SA, FA and TBT
resolution generally satisfy specification. Current, filling
pattern and temperature dependency are also adequate.
Mechanic stability is key issue beyond expectation when
it requires nano-meter level stability. The FA latency time
is around 150 േ 50 us.

ACKNOWLEDGEMENT
Thanks for the help form Y. S. Cheng, Y. T. Chang,and Demi Lee. The authors appreciate help from staffs ofI-Tech for brainstorming and discussion.

REFERENCES[1] TPS Design Handbook, version 16, June 2009.
[2] Instrumentation Technologies: http://www.i-tech.si.
[3] GDX Module Specifications v1.1.

50(b)Figure 13: (a) Histogram of 30-minutes satbility for 228
BPM modules. (b) 14 hours and 60 hours stability
observations for one BPM module.

ISBN 978-3-95450-119-9
Beam Position Monitor System

5c 2012 by the respective authors — cc Creative Commons Attribution 3.0 (CC BY 3.0)
Copyright ○LONG-TERM AND SHORT-TERM
STABILITY