InjectorbeamCommissioning
Injector
operation

Injector beam operation
Masanori Satohfor injector linac group1
KEKB Accelerator Review Committee,
July 8-10, 2019

Contents
1. Overview
2. Beam operation status
3. Recent progress
4. Summary
5. Future plan

2

Injector beam operation

Injector related subjects
1. Injector RF and LLRF (T. Miura)
2. Injector beam monitors (F. Miyahara)
3. RF gun (R. Zhang)
4. Positron source (Y. Enomoto)
5. Status of beam transport lines (T. Mori)
6. Emittance preservation (Y. Seimiya)
7. Control system (H. Kaji)3

Injector beam operation

Injector linac overview• Injector linac– e-/e+ injector for 4 independent storage rings, and e+ DR– 50 Hz, up to 2 bunches (96 ns interval)– Simultaneous top up injection to all rings• SuperKEKB:– HER: e-, 7 GeV, 1 nC
– LER: e+, 4 GeV, 1 nC
(DR: 1.1 GeV)

• Light sources:– PF:e-, 2.5 GeV, 0.3 nC– PF-AR: e-, 6.5/5 GeV, 0.3 nC

4Injector beam operation

Parameters (KEKB/sKEKB)KEKB (final)

SuperKEKB(Phase-I)

SuperKEKB(Phase-III final)

Beame+e–e+e–e+e–Energy (GeV)

3.5

8.0

4.0

7.0

4.0

7.0

Stored current (A)

1.6

1.1

11

3.6

2.6

Beam lifetime (min.)

150

200

100

10066

Primary e-10

Primary e- 8

Bunch charge (nC)

→11→ 0.4

Normalized
emittance (mm∙mrad)

1400

310

1000/1200

Energy spread (%)

0.125

0.125

# of bunch

22

Beam rep. (Hz)50

Simultaneous top up

3 rings(KEKB e–/e+, PF)

1

Primary e-10→44200/130

100/15(Hor./Ver.)

40/20(Hor./Ver.)

0.5

0.5

0.16

0.07

22222550

n/a4+1 rings(SuperKEKB e–/e+, DR,PF, PF-AR)

Injector beam operation

Injector linac beam operation• Photocathode RF gun for HER injection• Thermionic gun for LER, PF, PF-AR injectionAB

Low emittance RF e- gun
Thermionic DC e- gun
1.1 GeV

1.5 GeV (1.35 GeV after fire incident)

C

12e+DR

3e‐:Chicane

e+ target

45Pulsed quads, steering magnets
HER: 7 GeV e‐

4.219 GeVe+ target
1.5 GeVC

6Decelerate

e-same energy

1PF‐AR: 6.5 GeV e‐or 5 GeV

LER: 4 GeV e+
1.1 GeVe+2

PF: 2.5 GeV e‐34

Injector beam operation

5

Pulse to pulse switching:rf e- gun/thermionic e- gun

Thermionic DC e- gun(GU_AT)・e+ production e-: 10 nC (for LERinjection)・e- study/HER injection: 1 nC
・PF injection: 0.3 nC
・PF-AR injection: 0.3 nC

RF e- gun
（GR_A1 for HER injection）

Pulsed bends for simultaneous top up(since 2018 summer)

7

Injector beam operation

RF gunRF e- gunInjector beam operation
M. Yoshida, R. Zhang, X. Zhou

M. Yoshida, SuperKEKB
review, Mar. 14th, 20188

High bunch charge e- from rf gun

Hor. orbit

Ver. orbit～ 3 nC

Bunch charge

9Injector beam operation

Pulse to pulse
e-/e+ beam switching• Pulsed steering magnet control e- beam orbit．
• Low emittance e- beam goes through a hole at center of beam line.

W target ( mm)
w/ hole (2 mm) for e- beam

10

Injector beam operation

Pulse to pulse beam switchingfor simultaneous top up• Maximum repetition of e- beam w/ thermionic gun is limited up to 25 Hz.
• Heating issue of pulsed bend coil and chamber• New bend and vacuum chamber will be installed in summer 2020.

RF gunThermionicgun

11

Injector beam operation

6.5 GeV e-

Simultaneous beam operation w/
thermionic e- gun and rf e- gunHor. orbit
Ver. orbit
Bunch charge
rf gunThermionic gun and damping ringHor. orbit
Ver. orbit
Bunch charge
Thermionic gun
12

Thermionic gun

Injector beam operation

Stored current stability during simultaneous top up

13

6.25 Hz6.25 Hz4.16 Hz4.16 Hz

Injector beam operation

PF-AR 5 GeV injection (1)•••PF-AR 5 GeV operation to save operation cost
Common DC bend for PF/PF-AR beam transport line
Frequent parameter switching for quasi top up
for both of PF and PF-AR

DC bendfor PF/PF-AR

Pulsed bendfor PF/PFAR

14Injector beam operation

Auto parameter switch

PF-AR 5 GeV injection (2)•Typical operation mode
– PF injection: 3 min.
– Parameter switching: 10 s
– PF-AR injection: 30 s

420 mA

30 s

PF stored current

3 min.

55 mA
1.8%

0.07%

54 mA
419.7 mA

PF-AR stored current

Injector beam15 operation

Monitors(1)• Beam position monitor (x 103)
– Four strip line electrodes (x 97)• Measurement precision ~ 10 m– Eight strip line electrodes (x 6) (J-ARC, LTR x2, PF BT, HER BT, LER BT)•Profile monitor (x 104)
– Al2O3/CrO3 (AF995R, Demarquest Co.). (t: 1 mm, 0.1 mm), YAG:Ce (t: 0.1 mm)•

Wire scanner (WS) (x 6)– SectorA, B, C, 2, 3, 5•

Streak camera (ST) (x 3)– SectorA, C, 3
ST
WS

WS
WSWS

WSST

ST
16

Injector beam operationWS

Monitors (2)•RF (amplitude, phase) monitor (x 61)– Klystron output, SLED output, accelerating structure output (beam induced field), reference signal– average, peak, rms values

Archiver viewer
RF monitor
Waveform viewer
17Injector beam operation

T. Miura, H. Katagiri

Synchronized data acquisition••

Shot by shot information of all BPM, RF monitor, Pulsed magnet data are available.
Waveform type data including beam shot ID– Beam shot ID is delivered from event generator to event receiver via data buffer.

••

All data are archived in storage system up to 50 Hz.
Client software can get the data as waveform type EPICS PV.
Beam shot ID

BPM system

LIiBM:BPM_SYNC:DATA:KBE

waveform data
(4601 elements)
18

RF monitor system

Event generator

Beam shot ID

Beam shot ID

Pulsed magnet system

LIiRM:RFM_SYNC:DATA:KBE

LIiMG:PM:sync_data:IREAD

waveform data(1701 elements)

waveform data
(258 elements)

Injector beam operation••••

Pulsed magnet system

Pulsed quads (x 28) (w/ ceramic duct) and steering (x 36) were installed at Sector3
to Sector5 in 2017 (on movable girder).
Pulsed bend, additional quad and steering were installed in 2018 summer and wintershutdown.
PXIe based control system (Windows 8.1, LabVIEW, EPICS) have worked fine w/oany serious trouble.
Power supply stability: 0.01% (24 hours)
Pulsed magnet
BPM

19

Movable girder(remoteoperation
controllable, 10 m step)
Injector beam••Movable girder

Movable girder was tested in the beam line.
Beam position was measured by BPM.
Horizontal scan

-0.5 mm ~ +0.5mm

Vertical scan

SP_33_4（vertical）

SP_32_4 (horizontal)

Injector beam operation

Y. Enomoto

20Energy feedback loops (1)– SuperKEKB• e- (HER injection beam): J-ARC, BT• e+ (LER injection beam): J-ARC, LTR, ECS, BT– PF and PF-AR• J-ARC, BT
rf for energy control

J-ARC(KL_B5, B6)

beamBT(KL_51, 52)

ECS

LTR (e+)(KL_27, 28)
21

ECS (e+)(KL_51, 52)

Injector beam operatione- BTBT (e+)(KL_61)

Energy feedback loops (2)• Energy feedback core

– work as EPICS IOC for PID control• Control GUI– Set/Read feedback parameter, monitor location, actuator device(klystron)• Energy stability at BT line
– < 0.025%
ee+Beam energy deviation (%)

0.100

0.075

0.050

0.025

0.000
00:00

05:00

10:00

2215:00

HH:mm

20:00

Injector beam operation

Beam orbit feedback• Orbit feedback tool is ready.
• It can be deployed in any point.
– J-ARC, end of linac, …

• Large orbit drift (~ 1 mm) can be corrected within ~ 0.1 mm
w/ feedback.

23

Injector beam operation

Y. Seimiya

Dispersion measurement and correction
J-ARC

Designchicane• Horizontal dispersion leakage from J-ARC
causes the beam position jitter.
• Applying fudge factors to quads in J-ARC,
dispersion is well corrected.

After correction

Before correction

MeasuredDisp. correction
w/ quads

24

Injector beam operation

Y. Seimiya

Emittance measurement (~1 nC)
w/ multiple wire scanners
Examplese+: x/y ～120/2 mAB

1.1 GeV

1.5 GeV eC

12e-: x,y ～20 me-: x,y ～10~20 m

25e+: x/y ～120/6 m

DR

34

BT
#1 straight

5e-: x,y ～ 50～80 me-: x,y ～ 80 m
Final target (4 nC)

e-: x/y 40/20 me+: xbeam/y 100/15
m
Injector
operation

Recommendations of the 22nd Review
R24.1: Measure the energy spread and energy jitter at the end of the linac
and demonstrate that the required goals are met.
・Energy jitter @ BT < ~ 0.025%
・Energy spread: High precision profile monitor will be installed at BT
R24.2: Develop with priority automatic correction algorithms for criticalprocedures like the dispersion correction.
・Dispersion measurement and correction software is ready.
・Orbit and energy feedback tools are also working.
R24.3: Define a backup strategy for Phase III in case that the primary RF guncannot be used, e.g. by preparing a scenario of using the second RF gun.

・In the future, second rf gun will work as backup.
・Thermionic gun is a backup for a while.
26

Injector beam operation

Summary• Achievement of stable simultaneous top up injection toHER, LER, PF, and PF-AR w/ thermionic gun, rf gun,pulsed magnets• HER injection has been done w/ rf gun from PhaseIII day 1
to run end w/o any significant problem.
• Establish of PF (2.5 GeV)/PF-AR (5 GeV) injection
scheme (quasi top up)• Quick recover from fire incident (one night rf conditioning,two days beam tuning)• Energy feedback, orbit feedback loops, and other operation
tools
27

Injector beam operation

Future plan

• Increase e+ bunch charge (Y. Enomoto)– New flux concentrator in 2020

• RF gun improvement (R. Zhang)– Temperature stability in laser hat, laser profile monitor during top up in 2019
– Better vacuum and higher rf power, higher QE photocathode in 2020

• Pulsed bend (heating issue)– New bend will be installed in summer shutdown 2020.

• Low emittance preservation w/ high bunch charge (Y. Seimiya)– Alignment, movable girder of acc. structure (x7) will be tested w/ beam soon.
– Precise orbit control, wake field free steering• Synchronized data acquisition and analysis– All data (BPM, rf, pulsed magnet) are already archived.
– Integrated data analysis tool is under development.

28

Injector beam operation