Pulsed magnet control system using
COTS PXIE devices and LabVIEW
Yoshinori Enomoto (KEK)
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Introduction
Overview of the system
PXI / PXI express devices
SoftwareEvaluation and Operation
Summary

Key words : Event Timing System, EPICS, LabVIEW, PXI / PXI express1

Accelerator complex in KEK Tsukuba
PFPF-AR

SuperKEKB HER
SuperKEKB LER

2

Accelerator complex in KEK Tsukuba




4 rings and 1 linac
Two light source rings
PF, PF-AR
Two collider ringsSuperKEKB LER, HERParallel configuration
No booster ringAll storage rings
Full energy injection
Top-up injection
Two electron gunsRF gun for low emittanceinjection to SuperKEKB HER
Thermionic gun for highcharge (10 nC) to produce
large number of positrons
Positron injection to LER

Our linac is an all-in-one 3injector

Accelerator complex in KEK Tsukuba
KEKB

SuperKEKB

e-e+e-e+Life time(min.)

200

150

66Emittance
(μm)

310

1400

40/20
(H/V)

100/15(H/V)

Bunchcharge(nC)1144very short life time
a few min. interruption ofinjection is not acceptable.
small emittance and high bunchcharge requirements
common parameter operation
is no longer valid.

Simultaneous (shot by shot) injection with different magnet parameter at 50 Hz is necessary4

Beam energy and structure of our linac

Electron-Positroncommon optics

Replace with pulsed magnet



600 m long, 8 sectors
Maximize common energy section
to use DC magnets as much as
possible
Install pulsed magnets mainly insector 3 to sector 5
Bend2

Quadrupole

32

steering

585

How to realize?
Requirements
Low cost and high reliability
We need 100 unitFlexible settingOn / off control is not enough
Small sizecompatible with old DC power supply
High efficiency
compatible with old DC power supply
MRF Event Timing SystemCompatible with existent timing system

EPICS

Compatible with existent control system
Limited time and human resources fordevelopment
That is why I write software….
6How to realize?
Requirements
Low cost and high reliability
We need 100 unitFlexible settingOn / off control is not enough
Small sizecompatible with old DC power supply
High efficiency
compatible with old DC power supply
MRF Event Timing SystemCompatible with existent timing system
EPICSCompatible with existent control system
Limited time and human resources fordevelopment
That is why I write software….



Our strategy isSeparation of power and control unit.

Develop power circuit by ourselvesUse commercially available devices asmuch as possible for control system
Use LabVIEW for programming languageUse standard windows PC for CPU

6

How to realize?
Requirements
Low cost and high reliability
We need 100 unitFlexible settingOn / off control is not enough
Small sizecompatible with old DC power supply
High efficiency
compatible with old DC power supply
MRF Event Timing SystemCompatible with existent timing system

EPICS

Compatible with existent control system
Limited time and human resources fordevelopment
That is why I write software….

Our strategy is
Separation of power and control unit.
Develop power circuit by ourselvesUse commercially available devices asmuch as possible for control system
Use LabVIEW for programming languageUse standard windows PC for CPU

This is yet another solution for medium
scale system

6

How to realize?
Requirements
Low cost and high reliability
We need 100 unitFlexible settingOn / off control is not enough
Small sizecompatible with old DC power supply
High efficiency
compatible with old DC power supply
MRF Event Timing SystemCompatible with existent timing system

EPICS

Compatible with existent control system
Limited time and human resources fordevelopment
That is why I write software….

Our strategy is
Separation of power and control unit.

Develop power circuit by ourselves
Use commercially available devices asmuch as possible for control system
Use LabVIEW for programming languageUse standard windows PC for CPU

This is yet another solution for medium
scale system
Full custom

Catalog
product

Suitable System scale

Large

Small

Development costs

HighLow

Development time

Long

Short

flexibility

HighLow
6System configuration of the pulsed power supplies
CSS archiverStandard power supply unit (4 x quad + 4 x steering)
DC power supply

NASoperater´s machine

PXI express

Pulse driver(for quad)

DC power supply
controll server

cRIO(interlock and data logging)

Pulse driver(for steering)

DC power supply

PXI express(fast controll)pulse driver

event signalmagnet

PC

EPICS CALXI ver 1.3
NI network shared variablecRIO(interlock and data logging)LAN

standard unit

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Timing and fast control


Trigger signal
to ADC and DAC

Optical fiber

ADC NI PXIe-6356
8ch, 16 bit, 1MSa/s
DAC NI PXI-6733
8ch, 16 bit, 1MSa/s

Event receiver
MRF EVR-230



PXI express system is adopted for fast control of thepower supplies (8GB / s).
All of the intelligent functions are processed by PXI
express unit
Pulse driver works as a kind of power amplifier
Separation of control and power section makes it
possible for us to flexible installation of different
capacity of power supplies.
MRF(Micro-Research Finland) event receiver with PXIform factor is used for timing control
MRF event timing system is used as a master timing
system of our linac.
Mode and shot ID information are sent to the event
receiver via optical fiberMode determine the destination of the beam.
Shot ID is used for tagging the data.
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EPICS and LabVIEW

Declare PVs
https://www.ni.com/ja-jp/innovations/white-papers/12/introduction-to-epics.html

Dynamic declaration is possible
only by LabVIEW running onWindows

Get/put value
Process by value change event9Data flow in main program10

DAC output control
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
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Slew rate is limited by voltage of the power supply
Beam timing t3 is fixed 3 ms after trigger pulse.
Flat top width t2 is fixed 0.5 ms before t3
V1 is always 10 V
V2 is determined by value of output current
t1 is calculated from other parameters
DAC output is determined from these parameters

Minimize energy consumption
current output
DAC output

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Data flow in main program12

Data flow in main program12

Data flow in main program

Point data (8 ch x 1 point @ beam timing)is extracted from ADC data array (8 ch xwaveform) and stored in the PV withappropriate mode name12

Data flow in main program

Point data (8 ch x 1 point @ beam timing)is extracted from ADC data array (8 ch xwaveform) and stored in the PV withappropriate mode namePrefix:magnet name:type:mode
LIiMG:PF_32_4:IREAD_R:KBE
LIiMG:PF_32_4:IREAD_R:KBP
LIiMG:PF_32_4:IREAD_R:PFE:
12:

Data in log files
Mode number = destination of the beam
Current read backCurrent setting

Each low contains information about each pulse.
A new file is created when the size of previous one is larger than 10 MB.
Data size is about 3 TB / year in total.
13Trigger dropping rate

Difference of shot ID between adjacent pulses from log data for one day.

A few drop per day forone unit
50 Hz x 24 hour x 3600
sec = 4.32 million
Dropping rate is lessthan 1 ppm

Even though Windows in not areal-time OS, practically it works
as we want.
This is a kind of brute-force
solution.
Machine power and careful
software writing is important.

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Long term StabilityConcern about long term stability of the LabVIEW on
Windows. (I was asked by many people….)






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Long term StabilityConcern about long term stability of the LabVIEW on
Windows. (I was asked by many people….)
20 units are running (16 units for operation, 1 unit for testand 3 units for other purpose) for two years.





15

Long term StabilityConcern about long term stability of the LabVIEW on
Windows. (I was asked by many people….)
20 units are running (16 units for operation, 1 unit for testand 3 units for other purpose) for two years.
 There is no need to reboot PC during run (usually 3 to 6months) except for a few specific units.
Maybe due to HW issue15Long term StabilityConcern about long term stability of the LabVIEW on
Windows. (I was asked by many people….)
20 units are running (16 units for operation, 1 unit for testand 3 units for other purpose) for two years.
 There is no need to reboot PC during run (usually 3 to 6months) except for a few specific units.


Maybe due to HW issue

There is no need to restart software.

15

Long term StabilityConcern about long term stability of the LabVIEW onWindows. (I was asked by many people….)
20 units are running (16 units for operation, 1 unit for testand 3 units for other purpose) for two years.
 There is no need to reboot PC during run (usually 3 to 6months) except for a few specific units.


Maybe due to HW issue

There is no need to restart software.

Not perfect but acceptable
There are many devices which is less stable than this one….
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summary
About 100 pulsed magnet were installed to realize
simultaneous top up injection to 4 different storage rings
 Setting current and destination can be changed every 20 ms
 COTS devices are used for control system to reduce
development cost and time PXI / PXI express with MRF’s Event Timing System isadopted
 Software is written by LabVIEW with EPICS modules.
 Real-timeness and long term stability are not perfect but
acceptable for present operation.
16

members



K. Furukawa
Adviser, management of the project, timing system
T. Kamitani
Magnet design
F. MiyaharaTiming system
T. NatsuiEnergy recovery pulse driver
M. Satoh
Timing and control system, software
K. YokoyamaMagnet design
M. YoshidaEnergy recovery pulse driver
S. UshimotocRIO interlock and data acquisition system
H. Satome
Device driver for event receiverThank youfor your attention!

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