Beam Injection Control
Hiroshi Kaji

2Overview
Beam Injection Control consists of:Beam Gate & Injection Rate Control
Bucket Selection & Injection Timing Control

It manages beam injection
into two main rings
during last 4 months.

One of the most successful systems in the phase-1 operation.

3

Beam Gate & Injection Rate Control
The Beam Gate and Injection Rate are controlled from same panel.

Injection Rate Setting
Parameters aretransferred to LINAC
via Channel Access.

Current Limit Setting
Injection is stopped(Beam Gate is closed)
when the beam current
exceed these limits.

Beam Gate Control
Enable/disable e– gun
Gate signals aretransferred to LINAC via
dedicated optical network.

Mostly from KEKB

4Automatic Gate Control for Vacuum Scrubbing
Well established beam gate control system
realized the “nearly” top-up operation.

Beam Currents are kept within 5% from requested values.

Keep high beam current with Beam Gate Control

5:00

6:00

7:00

8:00

5

Beam Gate Hardware
VME type EPICS IOC (which manages also the beam abort signal)
Two kinds of Beam Gate control are implemented with FPGA based circuit.
- Open/Close from operation panel (via Channel Access)- Fast Close hard-wired with the abort signal

CA from operator

AnalogOut
LER abort

HER abort

LER Beam GateFPGA

HER Beam Gate

to LINAC

LER abort kicker trigger
HER abort kicker trigger

revolution

6

Bucket Selection
D7

Main Timing
StationReflective Memory
VMIVME-5565

Main Ring

Central Control
Building
Interaction
Point

RM

CPU

Optical Cable

BCM e+
BCM e–CPURM

IOC D7
Measure charge ofindividual bunches

RM

Adjust injection timing for
selecting RF-bucket

IOC Central Control
Indicate injection
RF-bucket

EVG
EVG
EVR
EVG
CPUIOC Main Timing Station

7

Bunch Current Equalizing
Turn BCE “ON” with following bunch current

Mean: 0.103 mA
RMS: 0.019 mA

Bunch Current(mA)

13 minutes after ...

Mean: 0.103 mA
RMS: 0.0087 mA

Bunch Current(mA)

8Event Timing System
MR Sub-timing Station is configured at Central Control Building.
The new Event Generator (EVG) is installed to enhance the capability of timing system.
It delivers 15 kinds of timing-triggers.
(BPMs at BT, kicker/septum magnets, other ring components ...)

MR
Sub-timing
StationMain
TimingStationMR
Sub-timingStation

9MR Sub-timing Station
MR Sub-timing Station is a state-of-the-art timing system.
We installed the EVG developed by Shanghai Institute of Applied Physics (SINAP).
Our Event Timing System is the mixture of MRF and SINAP modules.
The drift and jitter of upstream Event is cancelled by resynchronizing with Main Ring
RF clock.
The 15 kinds of timing-triggers are generated from only one Event-Code.

Injector Linac

MR Sub-timing Station

RF: 2856MHz
1/55

VME-EVG-230 (MRF)
Event clock: 114.24MHz

Other EVRs at LINAC

RF: 508.89MHz
1/7
distance~1km

EVG (SINAP)

EVR (SINAP)

Event clock: 72.70MHz

72.70MHzseptum/kicker magnets, ...10Picture of Sub-timing Station
Event fanout andtrigger monitoring system
EVG

Main part (EVG and EVRs)

EVRs

11RF synchronization
KEKB

LINAC

510MHz

~

1/51

1/51

~ 508.89MHz~ 571.2MHz
Phase-shifter

RF phase is switched between e+ and e–.
(This is controlled by the KEKB side.)

division/multiplication
10.385MHz

114.24MHz

571.2MHzThe RF phase switching (jumping) is not acceptable for some LINAC components.
- We cannot operate RF gun for e+/e– beam simultaneously.
- Event Timing System becomes unstable.
We will remove the phase-shifter at KEKB in run-2.

2856MHz12New Configuration in run-1
510MHzWe will test new configuration in the end of run-1. KEKB
- do not switch RF phase at the KEKB side
- Four local phase-shifters at LINAC
are switched between e– and e+ injections. Fix to e– ring

LINAC

1/51

Phase-shifters are switchedbetween e– and e+ injections.

114 .24 MHz

for RF Gun Laser system

division/multiplication

508 .9 MHz

To SuperKEKB for monitoring

Newly installed

2856 MHz571 .2 MHz・ ・ ・ ・ ・ ・ ・10 .385 MHz
114 .24 MHz
2856 MHzAT gun
trigger system

Grid pulser (gun-delay)

Tune delay

508.89MHz

571.2MHz

Frequency divider /multiplierdivision/multiplication

EVT1/51

SHB1
SHB 2
114 .24 MHz 571 .2 MHz

13SummaryInjection Control System plays an important role for SuperKEKB.
This is one of the most successful system in the run-1 operation.
It delivered a large amount of beam into two main rings.
Injection processes by LINAC are control from main ring side with arbitrary injection
rates.
Beam Gate Control system delivers fast and robust signals to LINAC for enablingand disabling electron gun.
It realizes the “nearly” top-up filling and helps the operation for vacuum scrubbing.
Bucket Selection manages the RF-bucket to be injected next beam-pulse andrealizes the requested fill pattern.
The “Bunch Current Equalizing” mode is working properly.

MR Sub-timing Station is configured at Central Control Building.
Newly installed EVG enhanced the capability of timing system.
One local set of EVG and EVRs provides 15 kinds of timing-triggers by the only one
Event-Code from LINAC.