Injector
InjectorCommissioning
Linac Status

Injector Linac Status
Masanori Satoh(Accelerator Laboratory, KEK)
for Linac Commissioning GroupThe 30th B2GM, June 18-22, 2018

Injector Linac Status

Contents
1. Injector Overview
2. Progress in Phase II
3. Towards Phase III
4. Schedule: Oct. 2018 5. Summary

Injector Linac Status

Injector overview• Injector for light sources (PF, PF-AR)3 times daily injection and SuperKEKB• up to 25 Hz beam repetition rate in Phase II (to save electricity)– 50 Hz operation in Phase III• Thermionic e- gun for light source injection and 10 nC beamgeneration (e+ production)• Photocathode rf gun for low emittance e- beam
• Flux concentrator, LAS (large aperture S-band) structure, solenoids for e+beam capture system• DR (damping ring) for low emittance e+ beam
Injector Linac Status

Energy profile for light source andSuperKEKB injectionAB

Low em ittance RF e- gun
Therm ionic 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-pulseswitchingby 50 Hz pulse-by-pulse for top-up injection.

Compatible settings for e-/e+ beams
1.1 GeVGeV e(DC1.5Quad)
DRC
1234e-:Chicanee+ target

HER: 7 GeV ePF-AR: 6.5 GeV e-

4.219 GeV
same energy

1.5 GeV

CDecelerate

ee+ target

15

1.1 GeVe+
2

LER: 4 GeV e+
PF: 2.5 GeV e-

3Injector Linac Status

45

• Monitors

Progress in Phase II– High measurement precision readout (< 10 µm) and synchronized measurementfor 100 beam position monitors (BPMs)• All data is stored together with shot id. Similar framework will be applied
to pulsed magnet power supply and rf monitor data for the correlation
analysis soon.
– Wire scanner at SectorB, SectorC, Sector2, Sector3, and Sector5– Streak camera at Laser hut/SectorA, SectorC, and Sector3– RF phase/amplitude monitors for klystron, SLED, acc. structure

••
•
•
•

Timing system for DR injection and extraction system
Stable operation of pulsed quads and steering magnets
Simultaneous beam injection via thermionic e- gunRF e- gun injection to HER (June 16th -)Beam energy stabilization

Injector Linac Status

Pulsed magnet
DC quad (triplet)

Pulsed quad

Pulsed steering• Pulsed quads (x28) (w/ ceramic duct) and steering magnets (x 36) on
new girder (Sep. 2017 - ) at Sector3 to Sector5• Power supply stability  0.01% (24 hours)• PXI bus based local controller and cRIO
• Remote controllable mover will be ready in this summer.
Injector Linac Status

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 Linac Status

RF e- gun

M. Yoshida, SuperKEKB review, Mar.Injector
14th, 2018 Linac Status

e- beam from photocathode rf gun
2 nd laser onlyX (mm)y (mm)Q (nC)

1.5 nC

1 st and 2 nd laser together
X (mm)y (mm)• Redundant Yb:Fiber + Nd:YAGHybrid Laser System• Three oscillators• Bunch charge– 3.6 nC @ first BPM– 2.4 nC @ Linac end(Phase II requirement: 1 nC)

Q (nC)

3.6 nC

2.4 nCInjector Linac Status

rf e- gun injection to HER
rf e- gunthermionic e- gun

Injector Linac Status

Emittance and bunch charge status
LER injection e+ beam

Normalized
emittance(Hor./Ver.)(mm·mrad)Bunch charge(nC)

HER injection e- beam

Goal

Current
statusGoal

Current status

200/40(w/ DR)

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

150/150

rf e- gun23.411  1.867/18.593  9.372@ SectorB
25.048  18.128/37.960  9.807@ SectorC
49.258  61.683/51.167  38.077@ Sector5
Thermionic e- gune.g.) 250/100 @ Sector50.51.4 (w/ flux concentrator)@ Sector5

1.0

1.0 (thermionic e- gun)@ Sector5
1.0 ~ 3.0 (rf e- gun)@ Sector5• Phase II parameters are almost achieved.
• Horizontal emittance of e+ beam and e- emittance at BT are large.
Injector Linac Status

Energy feedback,etc• Energy feedback at J-ARC, Sector2, Sector5 for each beam
operation mode (HER, LER, light source injection beam)• Energy fluctuation at BT: <  0.1%
• When klystron down at Linac:– Beam gate close => waiting for recovery of klystron ( 8 s ) => beam gate open

Energy stability of e- beam

Energy stability of e+ beam

Injector Linac Status

Towards Phase III• Investigation of– e- beam emittance growth at BT.
– large horizontal emittance of e+ beam

• Large misalignment at Sector2 (~ 2 mm)– will be fixed in this summer shutdown• Simultaneous top up for HER, LER, PF, PF-AR byusing rf e- gun and thermionic e- gun– Fast switching (50 Hz): rf e- gun and thermionic e- gun• Beam position jitter issue
Injector Linac Status

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

Thermionic DC e- gun(GU_AT)e+ production e-: 10 nC
e- study/HER injection: 1 nC
PF injection: 0.3 nC
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 by pulsed bendin summer shutdown

Injector Linac Status

Required injector parameters
KEKB (final)

Phase-I

Phase-II

SuperKEKB(final)

Beame+e–e+e–e+e–e+e–Energy

3.5 GeV

8.0GeV

4.0 GeV

7.0GeV

4.0 GeV

7.0GeV

4.0 GeV

7.0 GeVStored current

1.6 A

1.1 A

1A1A–

–

3.6 A

2.6 A

Life time (min.)

150

200

100100––66

Bunch charge(nC)

primary e10→11

primary e- 8
→ 0.4

1

0.5

1

primary e- 10
→44

Norm.
Emittance(gbe) (µrad)

1400

310

1000

130

200/40150

100/1540/20(Hor./Ver.)(Hor./Ver.)

Energy spread

0.125%

0.125%

0.5%

0.5%

0.16%

0.1%

0.16%

0.07%

Bunch / Pulse

22222222

Stage

Repetition rate
Simultaneous
top-up injection

50 Hz25 Hz(Hor./Ver.)

25 Hz

3 rings
No top-up
Eventually(LER, HER, PF) Injector
Linac Status

50 Hz
4+1 rings (LER, HER,DR, PF, PF-AR)

Beampositionjitterissue• e+ target w/ small beam hole for e- beam (f2 mm)• Small beam hole could cause the beam position jitter.
• Machine study plan:– Remove e+ target in this summer shut down and install test dummy target w/ small
hole of various diameter.
– e+ target will be back in winter shutdown for Phase IIIJ-ARC
hx ~ 0.8 (m)e+ target
Horizontal
VerticalInjector Linac Status

Schedule: Oct. 2018 -• Pulsed bend (thermionic/rf gun merger line), some pulsed
quads and steering installation in this summer shutdown• Flux concentrator reinstallation during winter shutdown• 50 Hz operation (will be tested in Dec. ‘18)
Injector Linac Status

Summary• Success of simultaneous injection to PF, PF-AR, HER, and LER fromthermionic e- gun.
• Timing system for DR, pulsed quads and steering magnets work well.
• Success of HER injection via rf e- gun• Required parameters for Phase II are almost achieved. e- emittance at BT
and horizontal emittance of e+ after DR should be improved.
• Towards Phase III– Simultaneous top up injection with thermionic/RF e- gun• Pulsed bends and quads installation (in this summer shutdown)– High bunch charge and low emittance preservation• Beam line alignment (in this summer shutdown)• Beam jitter study w/o e+ target (in Oct. – Dec., 2018)• Beam orbit control study (in Oct. – Dec., 2018)

Injector Linac Status