Injector Commissioning

Injector Commissioning
Masanori Satoh(Accelerator Laboratory, KEK)
for Linac Commissioning GroupThe 22nd KEKB Accelerator Review Committee, March 14-16, 2018

Contents
1. Injector Overview
2. Recent Commissioning Topics
3. Towards Phase II, III Commissioning
4. Operational Concerns
5. Summary and Plan

Injector Commissioning• Injector linac

Injector Overview– e-/e+ injector for 4 independent storage rings and e+ DR– 600 m, 25 Hz (up to 50 Hz)– Single or two bunch operation (96 ns interval) for SuperKEKB• SuperKEKB (Phase II):
– HER: e-, 7 GeV, 1 nC, 25 Hz– LER: e+, 4 GeV, 0.5 nC, 25 Hz
Damping ring: 1.1 GeV• Light sources:– PF:e-, 2.5 GeV, 0.3 nC, 5 Hz

three times daily injection or top-up
for hybrid operation– PF-AR: e-, 6.5 GeV, 0.3 nC, 5 Hz
three times daily injection

Injector CommissioningRecentCommissioning
Topics• PF, PF AR injection from GU_AT (@ SectorA) thermionic gun(previously GU_3T @ Sector3)• PF AR injection via new beam transport line
• Monitors– New BPM readout (high measurement precision) and synchronizedmeasurement– RF monitor. Wire scanner at Sector2 and Sector3. Streak camera at Sector3• Simultaneous beam operation w/ thermionic e- gun• RF e- source progress– M. Yoshida• Stable operation of pulsed quad and steering (Sector3 to Sector5)– Y. Enomoto• Timing system for DR injection and extraction– H. Sugimura• ECS and BCS for DR are working w/o significant trouble
Injector CommissioningBipartition Linac• Summer 2010  Summer 2017:• Concrete shield between Sector2 and Sector3.
• Downstream: GU_3T for PF and PF-AR injection• Upstream:Beam line works in tunnel
GR_A1 study @ SectorAB
B
A RF e- gun (GR_A1)
Thermionic e- gun (GU_AT)

Thermionic e- gun (GU_3T) forPF and PF-AR injection

1.5 GeV e-C

1e+ target

2

3

Concrete shield

Injector Commissioning45Removal of Concrete Shield• Summer 2017
• Construction of junction beam line between RTL and Linac• Removal of concreate shield and GU_3T thermionic e- gun• Light source injection w/ GU_AT e- gun• PF injection: Apr. 2017
• PF-AR injection: Feb. 2017

BARF gun (GR_A1)
Thermionic e- gun (GU_AT)
for PF, PF AR injection
1.1 GeV

1.5 GeV e-C

1e+ target

2DR3

Injector Commissioning

45

New PF AR BT for Full Energy Top Up Injection•During KEKB operation, PF-AR and KEKB share the long part of BT line. PF-AR
injection interrupts KEKB injection ~ 20 min. (sometimes 1 hour)•New PF-AR BT is required for SuperKEKB operation– Design work FY2012– New tunnel construction: FY2013 - 2014
– Installation of full components: FY2016– Success of beam commissioning: Feb. 13 – Mar. 10, 2017
• Day1: Deliver e- beam to end of new BT• Day2: Beam storage

H. Takaki (KEKB review 2013)

Injector Commissioning

PF, PF AR injection rate
PF AR injection rate (mA/s)
PF injection rate (mA/s)

2.5

GU_3T injection
PF-AR: 25 Hz injection

2.0
PF-AR w/ GU_AT, 5 Hz
Injection time 30 s (from 20 min.)

1.5

PF w/ GU_AT, 5 Hz

1.0
0.5
0.0
2015/09/08

2016/03/08

2016/09/08

2017/03/08

2017/09/08

Date (yyyy/MM/dd)
InjectorCommissioning

2018/03/08



Beam injection rate (mA/s)

3.0

Monitors• Beam position monitor (x 103)
– Four strip line electrodes (x 97)• Measurement precision ~ 10 µm– 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, 3ST
WS
WS

STWS
WSWS

ST

Injector CommissioningWSMeasurement
precisionofBPM• BPM readout system for 100 BPMs have been replaced byVME based card from digital oscilloscope.
• Achieve target performance (s ~ 10 µm)
Previous system
s: 50 ~ 100 µm

e+ target

Pulsed magnet
f12 mm10e+ target
Injector Commissioning

Sector3~
Sector5

Current system

Synchronized BPM measurement• Synchronized all BPM measurement frame work is
implemented as EPICS IOC.
• Beam shot ID is delivered from event generator (EVG) toevent receiver (EVR) via data buffer.
• EPICS PV contains all BPM data– horizontal beam position, vertical beam position, bunch charge,
average value, single shot value, …

• Some application software (beam orbit display, quad BPM,..) use this PV. Similar frame work is under developmentfor RF monitor.

Injector CommissioningBeam Operation Scheme towards
simultaneous top up injectionAB

Low emittance RF e- gun
Thermionic DC e- gun for positron
production and light source injection

l e-/e+ beams are delivered to 4-rings
PulsedQuad andwith different
bunchsteeringcharge andfor
energy.
l Beam acceleration modes must be switchedpulse-by-pulse
switchingby 50 Hz pulse-by-pulse for top-up injection.

Compatible settings for e-/e+ beams
1.1 GeV
1.5 GeV e(DC Quad)
DRC123e+ targetCHER: 7 GeV ePF-AR: 6.5 GeV e-

Decelerate LER: 4 GeV e+ee+ target

15e-:Chicane

4.219 GeV

same energy

1.5 GeV41.1 GeVe+
2PF: 2.5 GeV e-

3Injector Commissioning45

Pulsed Magnet Operation• Pulsed quad (x28) (w/ ceramic duct) and steering (x36) were installed mainly at Sector3 to Sector5 inlast summer shutdown. Mounted on new girder.
• For simultaneous top up for SuperKEKB HER/LER,PF, PF-AR.
• PXI bus based local control system on Windows8.1
and LabView (Y. Enomoto).
• cPCI bus based timing system (MRF EVR-230)• Total performance test w/o beam in Sep. 2017
Injector Commissioning

Simultaneous beam operation w/thermionic e- source
Hor. orbit
Ver. orbit
Bunch charge

Stable operation w/o significant trouble
Hor. orbit
Ver. orbit
Bunch charge

Injector Commissioning

Operation Software• Key application: Virtual Touch Panel– Control GUI for any parameters– Rewritten by Python (previous one by Tcl/Tk)
for adding pulsed magnet control.

• Energy feedback– At J-ARC, Sector2, LTR, ECS (LTR),Sector5– Implemented as EPICS IOC• Target Feedback at e+ target hole
– Can be applied for any locations

Injector CommissioningDispersion correction at 24 deg. line
Before correction

After correction

24 deg. vertical bend

24 deg. vertical bend

Hor. orbit• Beam energy of 1st and 2nd bunch
are different before fine tuning.
• At BPM (SP_A1_M) downstream
the 24 deg. junction beam line (twovertical bends), the vertical beam
orbit of 1st and 2nd bunch is muchdifferent.
• After correction, 1st and 2nd bunch
vertical orbits are almost the same.

Hor. correctorstrengthVer. orbit

Ver. corrector
strength

Bunch charge

Injector CommissioningEnergy correction for two bunch operation• 1st and 2nd bunch timing interval ~ 96 ns• For regular accelerator unit using SLED, rf timing isadjusted to equalize the beam energy of 1st and 2nd bunch.

• For rectangular RF output (w/o SLED), prefilling timing
injection for 1st bunch is applied for energy correction.
24 deg. junction

Injector CommissioningstndEnergy equalization of 1 and 2 bunchat acc. Unit AT
Before correction
Hor. orbit
Hor. corrector strengthVer. orbit
Ver. corrector strength

Bunch charge

Injector CommissioningstndEnergy equalization of 1 and 2 bunchat acc. Unit AT
After correction
Hor. orbit
Hor. corrector strengthVer. orbit
Ver. corrector strength

Bunch charge

Injector Commissioning

Towards Phase II• PF top up (hybrid operation) is planned in June.
• Frequent switch operation (rf/thermionic e- gun) is necessary.
• HER injection (rf gun) 1 min. => switch (10 s) => LER and PF
injection (1 min.) => switch,………
LER injection beam

HER injection beam

GoalCurrent
statusGoalCurrent status

Normalized
emittance(Hor./Ver.)(mm·mrad)(wire scannermeasurement)

200/40(w/ DR)

192  22.4 / 2.01  0.363@ Sector3
185  28.4 / 1.72  0.704@ Sector5

150/150~ 20 @ SectorB(rf e- gun)Bunch charge
(nC)

0.5

1.4 (w/ flux concentrator)@ Sector5

1.0

Injector Commissioning~ 100 @ Sector5(rf e- gun: Phase I)~ 160 / 300 @ Sector5(thermionic e- gun: PhaseI)
1.0 (thermionic e- gun)1.0 ~ 3.0 (rf e- gun)@ Sector5

Towards Phase III• Simultaneous top up w/ thermionic and RF e- gun is necessary.
Thermionic DC e- gun(GU_AT)

Replaced by pulsed quad
(unit A1 and A2)

e+ production e-: 10 nC
e- study: 1 nC
PF/PF-AR injection: 0.3 nC
BM_AT_J1

RF e- gun
GR_A1 for HER injection

BM_AT_J5

24 deg. junction line
DC bend will be replace bypulsed bendin summer or winter shutdown
RF e- gun
(GR_AS for study)
Injector Commissioning

2018/4/4

Towards Phase III
Thermionic DC e- gun(GU_AT)

Replaced by pulsed quad
(unit A1 and A2)

24 deg. junction line
DC bend will be replace bypulsed bendin summer or winter shutdown

Injector Commissioning

RF e- gun
GR_A1 for HER injectionOperational Concerns• RF breakdown problem of LAS unit (ACC17)– Sometimes, one or more shift is required for recovery.
– Stable e+ operation is difficult.

• At the thermionic e- gun station– Unstable temperature control at thermionic e- gun station• New air conditioner will be installed in the near future.

– EVR for thermionic e- gun timing sometimes stops. Several min.
is required for recovery.

• Unstable SHB#1 (114 MHz) amplifier– New amplifiers (also SHB#2 (571 MHz)) are now under test.

• Remote control of BM_AT_J1/J5 is unstable.
– New power supply is now under test.
Injector Commissioning

SHB amplifier
SHB #1 (114 MHz)
20 kW

SHB #2 (571 MHz)
10 kW

New SHB #2 (571 MHz)

1600 mm1950 mm

New SHB #1 (114 MHz)

1600 mm

Injector Commissioning

600 mmSummary and Plan
• Success of light sources injection (PF and PF-AR) via
GU_AT e- gun, and PF-AR full energy injection w/ newBT line.
• New BPM readout and synchronized measurement
framework work well.
• Simultaneous top up injection is ready by using thermionice- gun.
• Success and stable operation of pulsed quad and steering
magnets, and timing control of DR injection and extraction.
• Safety system and beam gate signal handling for DR work
well.
Injector Commissioning

Summary and Plan (cont’d)• Towards Phase II:– Almost required parameters have been achieved– Operational concerns should be solved.
– PF top-up operation (one week) is planed in June. Frequent switch
between thermionic and rf e- gun should be tested.

• Towards Phase III:
– Simultaneous top up injection by using both of thermionic and rfe- gun.
• Pulsed bend and quad will be installed at SectorA in this summer or wintershutdown.

– Low emittance preservation operation• Jitter (Y. Seimiya)• Alignment

Injector Commissioning

BackupInjector Commissioning

Parameters (KEKB/SKEKB)KEKB (final)

SuperKEKB(Phase-I)

SuperKEKB(Phase-III)

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 ()150200

10010066

Primary e-10

Primary e- 8

Bunch charge (nC)

→11→ 0.4

Normalizedemittance (mm·mrad)

1400

310

1000/1200

Energy spread (%)

0.125

0.125

# of bunch

22Beam rep. (Hz)50

Simultaneous top up

3 rings(KEKB e–/e+, PF)

1

Primary e-10→45200/130

100/15(Hor./Ver.)

40/20(Hor./Ver.)

0.5

0.5

0.1

0.1

22222550

n/a

4+1 rings(SuperKEKB e–/e+, DR,PF, PF-AR)

Injector Commissioning
28

••
•
•

Low emittance preservation

Low emittance e- beam transport w/o damping ringEmittance preservation w/ precise beam orbit control is key issue for e- beam.
Simulation results show the feasibility of emittance preservation w/ bunch
compression and offset injection. Beam study was also conducted.
Beam study was also conducted at Sector A and B (125 m straight section)•••- Simulation Quads and acc. w/
misalignment of 0.3 mm (s)50 different error seeds
All seeds can be corrected.

••- Experiment Control steering at Sector A
Emittance was changed at Sector B

Injector Commissioning