WAO2010< kazuro.furukawa @ kek.jp >Pulse-to-pulse Beam Modulation
for KEKB and PF Injections
andEnergy Management at KEK 8GeV Linac
K. Furukawa, N. Iida, T. Kamitani, Y. Ogawa,Y. Ohnishi, M. Satoh, T. Suwada,
S. Kusano, T. Kudo
KEK
< kazuro.Furukawa @ kek.jp >April 2010.
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Electron Accelerator Complex
Linac clients
KEKB
8-GeV e– 1nC x2
3.5-GeV e+ 1nC x2(with 10nC primary e–)

PF 2.5-GeV e– 0.1nC PF-AR 3-GeV e– 0.2nC

At first simultaneous
top-up injections to three rings at KEKB and PF
Switching beams at 50Hz
For stable operation and higher quality exp. results
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Operation
Operation groups at KEKB and linac
 Overlapped groups Many attend commissioning group from eq. groups Daily KCG meeting
KEKB
Linac
 Weekly LCG meeting
OperatorOperatorGroupGroupKEKB
CommissioningLinac
Group CommissioningGroup

KEKB Ring
Simultaneous Injection and Energy Management

Linac

Kazuro Furukawa, KEK, Apr.2010.

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KEKB Operation Improvement

Apr.2003
Dual Bunch e+May.2000

Feb.2005
ContinuousInjections
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Fast beam switching or Simultaneous Injection
Luminosity degradation on beam studies at PF andPF/AR
Future SuperKEKB injections with shorter lifetime
Sensitive luminosity tuning with Crab cavities
PF top-up injection for higher quality experiments
CERN/PS switches beams every 1.2s (PPM)SLAC/SLC switched beams at 180 Hz
KEK Linac had switched beams 360 times a day in 2008 (justbefore simultaneous injection)
10~120seconds per switching
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Requirements
Maximum beam rate of 50Hz x 2bunches should be kept
Most pulsed power supplies were designed to operate atconstant rate (a restriction)
Most linac magnets were not pulsed (except positronfocusing coil)Thus, it took much time for mag-field standardization

Approx. 1000 devices in linac
600 active devices (gun, RF, magnets, etc), 100 passive devices (BPM,WS, etc), and static devices

20ms beam switching became the solution

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Hardware and Operation Improvements
Separate BT for PF (2005)
Pulsed bending magnet for PF (2007)
PF beam from common gun (A1) (2007)
Beam charge safety interlock (2007)
Event-based fast control system (2008)
Pulsed steering magnets (2008)
Electron bypass hole at positron target (2008)
Interface between ring-linac RF (2008)
Multi-energy linac optics (2008)
Simultaneous injections (Apr.2009)
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Linac Energy ProfileBARC

12435Energy(GeV)

deceleratione-: 0.1nC

2.5 GeV → PF

1.7

8.0 GeV → HER

e-: 1.0nC

nacceleratio

1.7e-: 10nC

e+: 1nC

1.7

R
Simultaneous Injection and Energy Management

3.5 GeV → LER

end of LINAC
Kazuro Furukawa, KEK, Apr.2010.

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Linac Energy Management

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Power Management
Power management at each power source of 60 50-MW power sources
 In order to maximize the power But not to increase the trip rate Interlock at a reflection level VSWR of 1.4
 If a trip rate is higher, the voltage is lowered Surveyed statistically every week

Some sources will be stand-by state As backups, if the energy is enough KEKB e+ has several stand-by, KEKB e– has typically one

Energy conversion
 Energy gain = constant x sqrt( power )Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Cavity and Klystron DatabaseUpdated on replacements of klystrons and cavities Converted into control database

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Crest Phase Calibration
Each power source with slow phase shifter Energy measurement scanning the phase shifter Primitive but reliable, while there were several methods
 Chicken and egg issue exists on bootstrap
 If no beam at the end, no measurement possible

 Every several month at least after the long
shutdown
 Automated measurement takes ~2hours for 60 sources Result is saved as a reference to other software If the voltage was changed, nominal crest change isapplied (1kV => ~8degree) (to be measured later)
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Typical Automated Phase Calibration

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Energy Profile
8 driver klystrons with fast phase shifters
 Each manage ~8 high power klystrons
 Define the overall energy profile With Small phase angle (from the crest)
 Energy spread compensation depending on beam charge

4 klystrons with fast phase shifters
 Forming two energy-knobs to adjust the energies Before the arc and at the end of the linac

 Not to enlarge the energy spread Two klystrons are grouped

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Two-bunch Energy Equalization
Two bunch in a pulse Energy compensation
 Depending on beam chargeFast timing adjustment
 Automated measurement Same procedure As crest phase measurement
 With ns timing as a variable

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Energy Profile Calculation
KEKB e8GeVPF
2.5GeV600m Linac
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Beam Optics MatchingBased on energy profile, fudge factors, etc.
 Wire scannermeasurements
 Every several days
 Somewhat affectedby background noise Matching by apush button

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Quad Fudge Factor
Twiss parameter measurement with wire scanners
Fudge factor determination, last done in 2008
 Orbit Observation
with Single kicks
 Several iterations
 One wiring error
was found

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Fast Controls for Three Energy Profiles
8 driver klystrons with fast phase shifters
 for overall energy profile and energy spread comp.

Acceleration/stand-by for 60 klystrons
 for rough energy adjustment, for back-up

4 energy knob klystrons
 for final energy adjustment

SLED timing of LLRF at 8 driver klystrons
 for two-bunch in a pulse energy equalization

Parameter change every 20ms is necessary
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Simultaneous Injection and Fast Controls

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Fast Controls
~100 parameter switching within 20ms
Keep most of magnet fields with compatible optics
Control llrf to change energy

Pulsed magnet triggers and delays
Delays to keep the constant rate for certain power-supplies

LLRF phases and delays
Gun voltage and fine delay
Interface to bucket selection, etc
Ethernet-based controls are not reliable enough
FPGA and fiber-optic RocketIO might be the way ?
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Event System
Many accelerator system require timing signals andaccompanying information (event) Several primitive facilities are combined and used at KEKB and Linac
 Fast Timing signals are provided with delay module TD4/TD4V
 Need timing trigger and rf clock (Slow) Events are provided in another facility Combining Hardware and Software Event/Timing Systems which distribute the both timing and event aredeveloped at Argonne/SLS/Diamond, and are employed at manyinstitutes (Event Generator/Receiver) Fast Timing, rf clock, Hardware event, Software Interrupt, can be handled in
one combined system with a single fiber cable Especially in EPICS, event can be connected EPICS Event directly, sorecord/database programming is possible
RfTrigger

Eventgenerator

Event code

Simultaneous Injection and Energy Management

FanoutEvent receiver
Event receiver
Event receiver

Output/Input

Optical fiber link
Kazuro Furukawa, KEK, Apr.2010.

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Timing System

Old Timing Station

Simultaneous Injection and Energy Management

New Event Receiver Station
with 16 outputs

Kazuro Furukawa, KEK, Apr.2010.

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Event SystemSimultaneous Injection
to KEKB-HER, KEKB-LER, and PF
2.5GeV to 8GeV, 0.1nC to 10nC

Stable stored beam current at three rings
Should improve collision tuning with Crab cavities
Should improve the quality of experimental data at PF

Fast switching of many device parameters
In 20ms / 50Hz
Should be reliable because beam power is much different

MRF Series 230 Event Generator / ReceiverVxWorks 5.5.1, MVME5500 (Originally with RTEMS but…)
Timing precision less than 10ps is sufficient (TD4 provides 3ps)
Multi-mode fiber, and single-mode fiber for longer distance

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Event System Configuration
 MRF’s series-230 Event Generator / Receivers
 VME64x and VxWorks v5.5.1
114.24MHz event rate,
 EPICS R3.14.9 with DevSup v2.4.1
50Hz fiducials
 17 event receivers up to nowMore than hundred
50Hz-Analog/Timing data
Multi/single-mode fiber
Timing precision is < 10ps.
 < 1ps with external module.

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Synchronization Scheme
Synchronization Req.

for PFKEKB : < 30ps
PF : < 300~700ps

Linac SHB
114.24MHz
PFCircumference
Correction

Flip-flop
Flip-flop

PF Revolution
1.6 MHz

Flip-flop

50Hz

EventSystem

Linac rf isSynchronized to KEKB rf
Event Clock is114.24MHz
We have to manage

AC Line Sync.

BucketSelection

EventSystem

for KEKB

Clock
Fiducial
114.24 MHz

SHB1 Phase
Controlx5

Rubidium
SGHER/LER
Injection
Phase Control

571.2 MHz
10 MHzSGx52856 MHz
X 49 ÷ 275

KEKB HER/LER
Circumference
Correction

508.89 MHz

HER/LER
BucketSelection

Simultaneous Injection and Energy Management

SHB2 Phase
Control
Acc. Phase,
Timing Control

Circumferencecompensation
Bucket selection
Injection phase controls

508.89 MHz

÷ 512099.39 kHzKEKB Revolution

Kazuro Furukawa, KEK, Apr.2010.

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Beam Mode Pattern Generation
Pulse 1

Pulse 2

Pulse 3

Beam Mode 1

Beam Mode 2

Beam Mode 3

Pulse n………

Beam Mode n

Main eventcodes for ʻnʼ

n+1 …

Preparation eventcodes for ʻn+1ʼ

 Every pulse (every 20ms) corresponds to a beam mode 10 different beam modes are defined (for KEKB e+, etc)
 One beam mode may contain several event codesAt least one main code and a preparation code for the next pulse

 About 50 event codes are definedSome events correspond to many functions, and others to specific devices

 Beam pattern buffer length (n) can be 2 to 500 (20ms x 500 = 10 seconds)
 A new pattern can be loaded at the end of the previous pattern Otherwise, the pattern repeats forever.

 Main events and preparation events in sequence Main events trigger timing signals
 Preparation events trigger software to exchange analog and delay parameters
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Event Manipulation
Human Operator

Injection Programs

Arbitrate and Generate Beam Mode Pattern (in PythonTk)
considering priorities of the rings
equalizing pulsed power supply intervalin 4 arrays (waveforms) of length 2 (40ms) to 500 (10s)each element corresponds to a 20-ms time slot and a beam mode �Generate Events for the Next 20-ms Time Slot (in Event Generator)
reading two consecutive elements from the beam mode patterngenerate several events for the next pulse
generate preparation events for the next after next�

Generate Signals based on Received Events (in Event Receiver)generate pulsed signals as prepared in the previous time slot
program the signals (enable/disable, delays, etc) for the next
start to generate analog signals for the next�
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Beam Mode Pattern Generators
 Pattern panel arbitrates requests
 From downstream rings with priorities, or human operators
 There are several pattern rules due to pulse device features andlimitations
 Pattern arbitrator software was written in scripting languages to meetdaily changes during the commissioning stage
Remote controlled automatic pattern arbitrator

Manual pattern generator

Typical operation in 2009.
~25Hz for KEKB LER
~12.5Hz for KEKB HER
~0.5Hz for PF
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Parameters
Parameters switching via Event system
LLRF phase/timing : 14x4
HP RF timing : ~60
Gun voltages, picosecond delay : 4
Pulsed magnets/solenoid : 14
Injection phase : 2
Bucket selection : 2
BPM : ~100x3

Basically sufficient for fast beam mode switchingMore parameters comming
Integrity monitors
Improved slow beam feedback, fast feedback, etc.
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Linac Event System
Satisfies the requirements
Event rate : 114.24MHz (bit rate : ~2.3GHz)
Fiducial rate : 50Hz
Timing jitter (Short term) : ~8ps
No. of defined events : ~50
No. of receiver stations : 17
No. of Fast parameters : ~130
CPU stopped 4 times
since Sep.2008
for 18 stations
Simultaneous Injection and Energy Management

CPUEVGEVROpt. Fan-out

EVR & LLRF

Kazuro Furukawa, KEK, Apr.2010.

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Beam Current
Beam currents
are kept withinKEKB 1mA (~0.05%)
PF 0.05mA (~0.01%)

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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KEKB Operation Improvement
Belle/KEK

May.2000
Apr.2003
Dual Bunch e+Feb.2005
ContinuousInjections
Dec.2008
Crab Cavities andSimultaneous Injection
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Summary
Energy management of KEKB linac was successfully
applied to simultaneous injection
Covers 2.5GeV – 8GeV, 0.1nC – 10nC
Beam optics diagnosis down to ~1%

Simultaneous injection to HER/LER/PF wassuccessfulDevelopment and installation for various kind of hardware
Another layer of controls based on a fast event system
Pulse-to-pulse reprogramming of event system

Simultaneous injection
will be the base for SuperKEKB as well
Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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Thank you

Simultaneous Injection and Energy Management

Kazuro Furukawa, KEK, Apr.2010.

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