Event-based Timing and Control System
for Fast Beam Switching at KEK 8-GeV Linac
Kazuro Furukawa, Tsuyoshi Suwada, Masanori Satoh - High Energy Accelerator Research Organization (KEK)
Takuya Kudou, Shiro Kusano - Mitsubishi Electric System and Service (MELCO SC)
Artem Kazakov - Graduate University for Advanced Studies (SOKENDAI)
Liyang Zhao - Shanghai Institute of Applied Physics (SINAP)
The 8-GeV linac at KEK provides electrons and positrons toseveral accelerator facilities. The 50-Hz beam-mode switchingsystem has been constructed in order to realize the simultaneous
top-up injections for Photon Factory and the KEKB high- and lowenergy rings, which require different beam characteristics. An
event-based timing and control system was built to change theparameters of various accelerator components within 20 ms.

Event System Configuration

The components are spread over a 600-m linac and requirechanges to 100 timing and control parameters. The system has
been operated successfully since autumn 2008 and has been
improved on as beam operation experience has been accumulated.
It is expected to enhance the quality of the experiments at KEKBand PF. We describe the details of this new and improved control
system and present status of the accelerator operation.

Event System◆ MRF!s series-230 Event Generator / Receivers.
◆ Multi-mode (62 µm) and single-mode (10 µm) fibers.

Event GeneratorCentral◆ VME64x standard and VxWorks v5.5.1.
◆ 114.24MHz event rate,

50Hz fiducials.

◆ 13 event receivers for now.
◆ Timing precision is less than 10ps.

KL_B5/B6

SB_B◆ More than 100 50-Hz Analog/Timing PVs

SH_A1e! GunARC

e– BT (PF: 2.5GeV, 0.1nC)

Cont-ABC

KL_51/52
SB_2

SB_3

SB_4

e+ BT (KEKB: 3.5GeV, 2nC)

SB_5

Beam Mode Pattern Generatione+ Target
Cont-1

Cont-2

Cont-3Cont-4Cont-5e– BT (KEKB: 8GeV, 2nC,
PFAR: 3.0GeV, 0.1nC)

Event Receivers

Pulse 1

Pulse 2

Pulse 3

Beam Mode 1

Beam Mode 2

Beam Mode 3

Pulse n………

Beam Mode n◆ Every pulse (every 20ms) corresponds to a beam mode.
◆ 10 different beam modes are defined (for KEKB e+, etc).

RF Synchronization System◆ One beam mode contain several event codes.
EventSystem◆ 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.

for KEKB◆ Otherwise, the pattern repeats forever.

ClockFiducial◆ Pattern generator software arbitrates requests from downstream rings.

SHB1 Phase
Control

114.24 MHz◆ There are many pattern rules due to pulse device features and limitations.

x5

10 MHzRubidium SG

SHB2 Phase
Control

571.2 MHzHER/LER
Injection Phase
Control

Remote controlled automatic pattern arbitrator

Manual pattern generator

x5SGAcc. Phase,Timing Control

2856 MHzx 49 ÷ 275

KEKB
HER/LERCircumference
Correction508.89 MHz

508.89 MHz

÷ 5120HER/LER
BucketSelection

99.39 kHzKEKB Revolution

for PFKEKB HER/LER Beam current history

Linac SHB
114.24 MHz
PFCircumference
Correction

Flip-flop
Flip-flop

PF Revolution
1.6 MHz

50Hz

EventSystem◆ Automatic injection program or human operator

AC Line Sync.

Flip-flop

may change the beam mode pattern very often

BucketSelection◆ Typical operations at April 2009 is◆ KEKB HER ~12.5Hz◆ KEKB LER ~25Hz◆ PF 0.5Hz◆ As stable operation was achieved,

RF Controls

Beam Instrumentation

Fiber

EventEvent
Receiver

DAC

ADC

VME
VxWorks
EPICS

EventAnalog
Timingllrf

Ethernet/CA

Oscilloscopewith Windowsand EPICS

Position&Charge
Beam mode

BPM x 4~6
◆ Slow rf controls are replaced with fast event systems.

◆ DPO7104 with embedded EPICS can acquire data at 50Hz .

◆ Timing and analog signals are essential for absolute energy,◆ Beam modes are recognized by events through network.

energy spread, and dual-bunch energy equalization.
◆ Signals can be switched pulse-by-pulse.
◆ Driver klystrons (SB), energy tuner klystrons (KL), andsub-harmonic bunchers (SH) are managed.

◆ Clients can monitor data of an interested beam mode.
◆ 100 BPMs are synchronized.

the rates will be lower.

Summary◆ The system successfully runs since summer 2008.
◆ Simultaneous injections are carried for 3 rings.
◆ Beam current stabilities (as of April 2009)◆ KEKB HER / LER : within ~2mA (12.5 - 25Hz)◆ PF ring : within ~0.1mA (0.5Hz)◆ Will be further improved◆ Integrity monitor system◆ Beam and equipment monitor system◆ Beam operation scheme