KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Multi-Tier Accelerator Control System
at KEK 8-GeV e–/e+ Linac
Kazuro Furukawa and Norihiko Kamikubota
KEK<kazuro.furukawa@kek.jp>

KEK 8-GeV linac injects electron and positron beams into the storage rings at
B-factory (KEKB), Photon Factory (PF) and PF-AR. Because of frequent switching
between these beam modes, a reliable beam operation of the linac is crucial. For
this end a multi-tier control system has been developed and used. The lower-layer
servers abstract hardware characteristics and the upper-layer server represents theproperty of accelerator equipment and the beam to the operation software. It also
provides the interface to the downstream storage rings, which are operated bydifferent control systems. The network and computer systems employ highavailability technologies in order to increase the reliability. Using these control
services many pieces of operation software have been developed. They all provide
essential functions to maintain the stable operation of the linac.

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

I. Introduction, KEKB Linacu KEKB Asymmetric Collider Complex andBelle Detector for CP-Violation Studyu Stable and Robust Operation of Linac
for Higher Experiment Efficiency
u Many Active Operation Parametersat Microwave Systems, etc.
u Frequent Switching between

KEKB e– 8 GeV 1.28 nC Single Bunch
KEKB e+ 3.5 GeV 0.64 nC Single Bunch(Primary e– 10 nC)
PF e–PFAR e–

2.5 GeV 0.2 nC Multibunch
2.5 GeV 0.2 nC Multibunch

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Linac / Ring Upgrade and Commissioningu 1995 - 1998, Upgrade from 2.5GeV 0.1nC to 8GeV or 10nC
x2.5 Acceleration Gradient with Energy Doubler (SLED)
40% Extension with J-shape because of the Site Limit
Continuing Injection to PF during Construction
u 1998 - Linac Commissioning
Overcome many Issues on Beam Physics, Stability, etc.
Indispensable for the Design and Constructionof the Next Generation Accelerators
u 1999 - Ring Commissioning and Operation
40 Persons in Commissioning Group (KCG),
Linac Commissioning Group (LCG, 20) is a part of KCG
All Linac/Ring Operation from KEKB Control RoomStruggling with Beam Size, High-Current (Heating)Peak Luminosity 30 x 1032 /cm2/sec, Int. Lum. 17/fb
Improving Daily !!
K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Layout of KEKB Linac
u 600m Linac with 59 S-band rf Stations,
Most of them has SLED with Gain of 160MeV
u Double (114MHz, 571MHz) Sub-Harmonic Bunchers
to Achieve 10ps and 10nC Bunchu ~700 Magnets for Beam Transport and ~100 BPM’s, etc.
Sector B

180-deg.
ArcSector C

Sector A

C-Gun

A-Gun
Positron Source

Sector 1

Sector 2

PF
Sector 3

Sector 4

Sector 5

Beam SwitchyardKEKB

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

II. Linac Control System Overview
u Rejuvenation in 1993
with a New Equipment-Oriented Designu Unix, VME, TCP/IP,
International and de-facto Standards
u Old Field Controllers Kept Runningu No Strict Standard for Field Controllers
but Diskless and Ethernet/UDP at Leastu Redundant Unix Servers and Networks
u Multi-tier Server Software for Beam/Equipment Servicesu Homemade RPC Protocol at both Internal / Externalu Upper Layer Software Hides Lower Layer Differences
u Memory-Resident Hashed Databaseand Cached Field Informationu Not an EPICS System but Has Gateway to It
K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control SystemControl Network Systemu FDDI and 100Base-Tx Ethernet at Center(about 100 computers/controllers)
u 10Base-FL/100Base-Fx (Optical) Ethernet at Fields
to Avoid Klystron Noises
u About 240 10Base-FL Field Controllersu Layered Switches and Repeaters in Star Topology
u Redundant Configuration at Central Networkand Upper Field Networks

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control SystemTouch Panel Interface

X-Window Interface for Operation

EPICS Gateway to KEKB-Ring

MS-Windows Interface

Central Network (FDDI, Ethernet)
Device Manager

Main Computer Systems (Unix)
Equipment Level Network (Optical Ethernet)

VME's (~30)(and Loop-3)

PLC's (~150)

CAMAC's (~15)

VXI's (~30)

PC / GPIB / RS232C

Beam Monitor
MagnetTimingetc.

RFMagnet
VacuumTimingRF Monitor

Gun
Beam Monitor
othersThere are many kinds of local controllers, but they all communicate through UDP/RPC
over switched redundant optical Ethernet segments.

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Network Configuration of Linac Controls
SwitchRepeater

Console Systems
SwitchDual FDDI Network (Star)

Redundant
Transceiver

SwitchRepeater
SwitchSwitchSwitchRedundant Transceivers and Repeaters
Transceiver

Field Controllers (~240)

Controller

33 field network stations are connected with central switches on FDDI through redundant 10Base-FL
Ethernet. Each station is connected to 4 to 10 field controllers. All connections at fields use 10Base-FL
because of the klystron noises. Network traffic at important points are monitored via SNMP.

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

III. Multi-Tier Architecture in Linac Controlsu Providing Accelerator Oriented Services at the Topu Accommodating Many Different Kindof Physical and Virtual Components
u Should Survive Long Termin spite of Technology Advance
Replacing/Adding Part by Part
u Robust but Flexible by Natureu Opposite Direction to EPICS in Some Sense,
but Works with EPICS at KEKB Ring

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Accelerator Equipment Oriented andBeam Parameter Oriented Services
u Instead of Channels, A Server Represents
a Group of Meaningful Information at Each Levelu Each Level Consists of Several Different Servers
and May Communicate with Upper and Lower Levels
u Some Services are Useful for Engineering Works
Such as Calibrations and Troubleshooting
and are Used by Upper Level Servers as wellu Other Services are Useful for Advanced Operations
and are Used by Beam Feedback Loops or Physicistsu Layered Architecturewith well-defined Interface is Important
K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Plug-in Servers Ease Future Upgradeu Easy to Add New Servers at the Topor to Add New Hardware at the Bottom
or Even to Replace a Middle Level Server
u Already Have been Working for 8 Years,
Have Supported KEKB Commissioning
and Still Are Improvingu Accommodating 20-Year-Old Controllers
and Recent Network Based Controllers
at the Same Timeu Most Services Are Synchronous,
While New Services Supports Asynchronous Access

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Advanced Beam Operations & Beam Study

Upper Level Servers

EngineeringOperations

Routine Operations

Middle Level Servers

Lower Level Servers

Network Based Hardware Controllers
Accelerator EquipmentEach lower layer software
supports corresponding fieldcontrollers. Upper layer software
hide differences between
controllers and serves accelerator
equipment controls to clients.
While UDP-based RPC protocol isused at lower layer, upper layer
make use of TCP-based one.

Electron / Positron Beams
K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

IV. Performance of KEKB Linac

Control Operation Examples

u4 Downstream Rings Require Quite Different Beams
u Switching Reproducibility and Reliability are Crucial
u 7300 hours of Operation in FY1999But Only 73 hours of Beam Loss Time
RingParticle
EnergyChargeBunch
Repetition
StoreTimeInterval

HER
LERPF
electron positron electron
8 GeV
3.5 GeV 2.5 GeV
1.28 nC 0.64 nC
0.2 nC(primary 10 nC)
singlesingle
1 ns
50 Hz
50 Hz
25 Hz
580 mA 780 mA 400 mA
1-2 min 4-10min 3-5 min
1-2 hr
1-2 hr24 hr

PF-ARelectron
2.5 GeV
0.2 nC
1 ns
25 Hz
40 mA
2-5 min
2-4 hrK.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Beam Feedback Loopsu More than 30
Software Feedback Loops
u Energy Feedback
Beam Position

Beam - rf Phaseu Orbit Feedback and Others
Beam Orbits
Steerings

Weighed Average of BPM's

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Beam Mode Switchu Reproducibility ofLinac Equipment Parameters
and then Beam Parameters
u Easily Re-configurable Automatic
Beam Mode Switch
u Fast and Robustwith Failure Recovery
u Visual Feedback
u About 50 Times a Day

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control SystemExample of Beam Intensity/Position Display (e+)

u Positron Beam of 0.8nC was Achieved at the end of Linac
K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control SystemV. Conclusion
u Network-Based Multi-Tier Server SchemeWorks Well in Linac Control Systemu It Have been Supported KEKB Linac Upgrade, Commissioning
and Advanced Operations in KEKB Accelerator Complex
u It Will Ease the Future Upgrade as Wellu Plan to Incorporate Other Control Protocols Such as CORBA
to Make More Tight Communication between Accelerators

K.Furukawa, HEACC 2001, Mar.2001.KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Linac Beam Parameters & Stability
u Precise Tuning of the Beam Parameters
Energy, Orbit, Emittance, Energy Spread,
Bunch Profile, Bunch Charge, Beam Timingu Simultaneous Fluctuation ofElectric Power or Temperatureu Interim Failure of Linac Equipmentu (may Lead to KEKB Luminosity Degradation)u (Linac/Ring Equipment may be Damaged)

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Beam Parameter Fluctuation & Stabilization
u If certain Instability was Observed;u Multi-Parameter Tolerance Study was Carriedu We may have to Hunt the Source
to Fix the Problem (if possible) or to Form a Closed Loopu To Find the Source, Correlation Analysis
and Singular Value Decomposition (SVD)u Often the Source is Attributed to the Linac Injector Section
where Many Devices/Parameters Resideu Feedback Loop without Resolving the Real Source
Choosing certain Pair of Monitor & Tuner, Still Effectiveu (Instead of Simple Feedback, Sophisticated Method like
Downhill Simplex or Global Orbit Correction
But Important Defects may be Hidden)
K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control SystemTolerance Study to Understand Fluctuationsu Single-Parameter Tolerance to Keep 90 % ofOptimal Beam at Positron Target
u Good Reference to Consider the Beam Stability
u With Multi-Parameter Drifts, More Tight Limitsu Improved Surveillance Systems for rf and Timing Systems
as well as Feedback Loops
Gun Beam timing
Gun high voltage
SHB1 (114MHz) phase
SHB2 (571MHz) phase
Buncher phase
Buncher power
Sub-booster-A phase
Sub-booster-B phase±45 ps±0.38 %
±1.1 deg±1.3 deg±1.7 deg±0.47 %
±3.5 deg±4.0 deg
K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Beam Monitors
u Computer Readable Beam Instrumentation
Strip-line type Beam Position Monitors (BPM)
Streak Cameras for Beam Bunch Profile
Wire Scanners for Transverse Beam Profileu To Find the Beam Energy
BPM Readout where Dispersion is Largeu Noise: External Electric Noise mainly from Klystrons
Optimized with Integration/Frequency, Resolution, Dispersion
u Noise: Beam Orbit Fluctuation (Betatron Oscillation)
Can be Derived from Orbit at Straight Section
e--GunARC[R0]

BCS[17]e+-Target

ECS[61]e--BT(KEKB,AR)e--BT(PF)e+-BT(KEKB)

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Two-Bunch Acceleration Study1u Loading Evaluation
Comparing Beams
0.99
of 8nC & 0.8nC
0.98
u Relation between
Energy vs. Timing
0.97
u Results Seems to bePromising
0.96
u Just Succeeded Test Injection
u Will soon Install0.95-100Feedbacks,
Beam Monitor Upgrades
Bunch Selection Upgrades

Second bunch

First bunch
96.29 ns-50

050100

Gun Timing [ns]K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Design Beam and Achieved Performance(1) Gun(2) Buncher(3) Arc(4) e+ target(5) e+ Solenoid exit
(6) Linac end

EnergyIntensity
Pulse width
EnergyEnergy spread (σ)
Intensity
Efficiency
Emittance γβε (σ)
Bunch width
EnergyEnergy spread (σ)
Jitters (p-p)
Drift (with feedback)Emittance γβε (σ)
TransmissionEnergy
Intensity
Transmission
Intensity
Specific yield
EnergyEnergy spread (σ)
Intensity
Specific yield
Transmission
Emittance γβε (σ)
Pulse repetition

keV
nC/pulsens
MeV
MeV
nC/pulse
mmps
GeV
MeV

8-GeV electron
Goal Achieved
200
200
1.5
22
1.8
1616
1.4

0.06
5
1.5
0.6%

mm

0.17
100%

GeV
nC/pulse
nC/pulse
e+/e-GeV
GeV
MeV
nC/pulse
e+/e-GeVmm
pps

1.9
95%
0.04
6
1.7
0.29%

80.15%
1.28>80.05%
>1.28

0.25
50>80%
0.31
50

3.5-GeV positron
Goal Achieved
200200131422.8151522>10
1190%
0.06
0.08
16
10
1.5
1.7
0.6%
0.38%
0.1%
<0.2%/h1.7>95%100%
3.7
3.7>10
1096%
2.4
6.8%
3.5>3.5
0.125%
0.15%
>0.64
0.82
2.3%
1.5
50

1.4
50

K.Furukawa, HEACC 2001, Mar.2001.

KEK 8-GeV e–/e+ Linac, Multi-Tier Accelerator Control System

Operation Application(Parameter Handling, etc.)

Scientific Application(Simulation, etc.)

Upper Layer Control Service(Beam Parameter, RF, Magnet, etc.)

Lower Layer Control Service(PLC, CAMAC, Loop3, etc.)
StaticDatabase

Engineering Application(Calibration, etc.)

Alarm andHistory Service

ArchiveDynamicDatabase

Field Control Hardware

Each lower layer software supports corresponding field controllers. Upper layer software hide differences betweencontrollers and serves accelerator equipment controls to clients. While UDP-based RPC protocol is used at lower layer,
upper layer make use of TCP-based one.

K.Furukawa, HEACC 2001, Mar.2001.