v1

Injector Linac Overview

Kazuro Furukawa
for Injector Linac, SuperKEKB

Injector Linac Status

K.Furukawa, ARC2018, Mar.2018

1

Injector Linac Mission

Mission of Electron/positron Injector in SuperKEKB
v For 40-times higher luminosity in SuperKEKB collider
v Low emittance & low energy spread injection beams with 4 times higher beam current³ New high-current photo-cathode RF gun³ New positron capture section³ Positron damping ring injection/extraction³ Optimized beam optics and correction³ Precise beam orbit control with long-baseline alignment³ Simultaneous top-up injection to DR/HER/LER/PF/PFARv Balanced injection for the both photon science andelementary particle physics experiments
Low emittance
RF-gunDamping
Ringe–Injector Linace+600 m

High efficiency
e+ generator

2x beamcurrent

PF
2.5 GeV

e–e+ BTPF-AR
6.5 GeVe – BT

Beam from Injector and Storage Current
SuperKEKB:
7 GeV e2600 mA
4 GeV e+3600 mA
PF:
2.5 GeV e450 mA
PF-AR:
6.5 GeV e60 mA

HER
7 GeV

SuperKEKB
3 km

LER
4 GeV

Belle II
40xLuminosity

Injector Linac Status

The single injector would behave as
multiple injectors to multiple storagerings by the concept of virtual
accelerator
K.Furukawa, ARC2018, Mar.2018

2Linac Beam Property Requirements

Required injector beam parametersStage

KEKB (final)

Phase-I

Phase-II

SuperKEKB(final)

Beame+e–e+e–e+e–e+e–

Energy3.5 GeV

8.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeVStored current

1.6 A

1.1 A

1A

1A

1.8 A

1.3 A

3.6 A

2.6 A

Life time (min.)

150

200

100

100––

66

Bunch charge (nC)primary e- 10→11

primary e- 8→ 0.4

10.5

1

primary e- 10→44Norm. Emittance(γβε) (µrad)

1400

310

1000

130

200/40(Hor./Ver.)150

100/15(Hor./Ver.)

40/20(Hor./Ver.)

Energy spread

0.125%

0.125%

0.5%

0.5%

0.16%

0.1%

0.16%

0.07%

Bunch / Pulse

22222222

Repetition rate

50 Hz

25 Hz

25 Hz

50 Hz

Simultaneous topup injection (PPM)

3 rings(LER, HER, PF)

No top-up

Eventually

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

Injector Linac Status

K.Furukawa, ARC2018, Mar.2018

3Schedule

RF-Gun e- beamcommissioning
at A,B-sector

Linac Schedule Overview as of Mar.2018
e- commiss.
at A,B,R,C,1

e+ commiss.
at 1,2 sector (FC, DCS, Qe- 50%)e- commiss.
at 1,2,3,4,5 sector

Phase1: high emittance beam for vacuum scrub
Phase2,3: low emittance beam for collision

Time →Location↓Beam
Licensesin steps

Low
Emittance
Beams

Low
Emittance
Injections

4+1 Ring
Injections

DRCommiss.
1 nC
Phase1

Without Top-up: Electron: Positron: Low current electron

Injector Linac Status

non damped e+ commiss.
at 1,2, 3,4,5 sectors
e- commiss. at A→5 sectors

1 - 2 nC
Phase22 - 4 nC
Phase3

Direct PF-AR BT
damped e+ commiss. Improved
at 1→5 Qe+ = 1~4nC RF gune- commiss.
at A→5 Qe- = 1~4nC

K.Furukawa, ARC2018, Mar.2018

4Injector-related Subjects to Discussu Injector Overview
u RF Gun – Mitsuhiro Yoshida
v Performance improvement in Phase-1, 2 and development for Phase-3

u Accelerating Structure – Hiroyasu Ego
v Accelerating structure performance and degradation recovery

u Pulsed Magnet – Yoshinori Enomotov Home-grown components for pulse-to-pulse controls in simultaneous injectionu Positron Generation – Yoshinori Enomotov Performance with damping ring and recovery from discharge issues

u Injector Commissioning – Masanori Satohv Injector performance in Phase 1, 2 and planning for Phase-3

u Beam Jitters – Yuji Seimiya
v Unexpected beam jitter observation after target holeu Timing Controls – Hitoshi Sugimurav Damping ring injection/extraction and bucket selection with main rings

u LTR & RTL commissioning – Naoko Iidav Evaluation of beam manipulation at damping ring injection/extraction
Injector Linac Status

K.Furukawa, ARC2018, Mar.2018

5Other Improvements

Examples of Other Recent Improvementsu Energy and bunch compressors on the beam transport of DRu Beam lines and power supply rearrangement for DR BT
u Thermionic gun and bunchersu Beam position monitorsu Wire scanners and streak cameras
u LLRF system to co-op with event timing controlsu LLRF monitors
u Independent RF amplifiersu Alignmentu Direct beam transport to PF-AR
u Safety system and radiation control licenses
u Rejuvenation of old components
u Operation softwareu Operation manuals
Injector Linac Status

K.Furukawa, ARC2018, Mar.2018

6Other Improvements

DR LTR / RTL Waveguidesnnn

Accelerating
structures for energy /bunch compressors on
DR LTR / RTL beamlines
45-m waveguides fromlinac gallery
Fabrication errors of~150 µm were found(while schematics from
KEK and from makerwere correct)
Linac

Injector Linac Status

DRRTL

K.Furukawa, ARC2018, Mar.2018

7

Other Improvements

DR LTR / RTL Waveguidesnn

17 waveguides

Bunch Compressor on RTL
Injector Linac Status

Components with red
circles had to bereplaced(Sep - Nov.2017)
Successfullycommissioned(Dec.2017)12 waveguides

Energy Compressor on LTR
K.Furukawa, ARC2018, Mar.20188Other Improvements

Klystron Modulator Installation
and Temporary Gun Removal

ECSBCS

Voltage required [MV]

41

21.5

# 2m accelerator
structure

2

1Accelerator field [MV/m]

10.2

10.75

Operation power [MW]

29.0

19.0

Pulse width [µs]

0.8

0.8

Rep. rate [Hz]5050

Injector Linac Status

KL_DS/BCS

KL_DN/ECS

KL_32
K.Furukawa, ARC2018, Mar.2018

Domestic Review

SuperKEKB Domestic Review
uThe third domestic review meetingw On September 8th, 2017
w Reviewers of Atsushi Enomoto, Katsunobu Oide (chair), Kotaro Satoh,Fujio Naito, Tatsuo Nakada, Junji Haba, Kentaro Harada, Yosuke
Honda, Shinichiro Michizono
w <http://accphys.kek.jp/indico/conferenceDisplay.py?confId=122>

vPositron source
vPhoto cathode RF gun
vAccelerating structure
vPulsed magnets

vDR timing system
vQCS
vLuminosity tuningvElectron cloud instability inPhase 1 operationvBeam background, MDI³Two of them received recommendations
Injector Linac Status

K.Furukawa, ARC2018, Mar.201810

Domestic Review

Positron source
uRecommendationvAvoid a fatal destruction by securing the dischargeinterlock activation within a pulse.
³==> The interlock system was re-examined, and it isbelieved that it did work within a pulse. (However, thepulse-to-pulse recording system was not working at thetime. It should be made robust.)

uConsiderationvFC may provide 20% increase from 6 kA to 12 kA³Balanced man-power distribution should be necessary
Injector Linac Status

K.Furukawa, ARC2018, Mar.201811

Domestic Review

RF gunuRecommendations
vNew technologies seem to be introduced too often.
Further discussions on available facilities arenecessary.
³==> Weekly meetings are held at the linac open space, inwhich members from other groups participate. Dr. Yosuke
Honda, one of the reviewers, further contributes to the laser
discussion weekly.

vConsidering whole operation would stop on the gunfailure, an existent technology should be employed³==> As was recommended in past review meetings,
existent technologies were applied for Phase-2. However,
we are still open to Phase-3 options.
Injector Linac Status

K.Furukawa, ARC2018, Mar.201812Summaryu Injector is ready for Phase-2 commissioning
incorporating recommendations in the past reviews.
u The facility is believed to be ready for the first year in
Phase-3 while it may face challenges to achieve the final
beam qualities.

Injector Linac Status

K.Furukawa, ARC2018, Mar.201813

Thank you

Injector Linac Status

K.Furukawa, ARC2018, Mar.201814

Injector Linac Status

K.Furukawa, ARC2018, Mar.201815

Linac Beam Property Requirements

Required injector beam parametersStage

KEKB (final)

Phase-I

Phase-II

SuperKEKB(final)

Beame+

e–e+e–e+e–e+e–

Energy3.5 GeV

8.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeVStored current

1.6 A

1.1 A

1A1A

1.8 A

1.3 A

3.6 A

2.6 A

Life time (min.)

150

200

100100––66

Bunch charge (nC)primary e- 10→11

primary e- 8→ 0.4

10.5

1

primary e- 10→44

Norm. Emittance(γβε) (µrad)

1400

310

1000

130

200/40(Hor./Ver.)150

100/15(Hor./Ver.)

40/20(Hor./Ver.)

Energy spread

0.125%

0.125%

0.5%

0.5%

0.16%

0.1%

0.16%

0.07%

Bunch / Pulse

22222222

Repetition rate

50 Hz

25 Hz

25 Hz50 Hz

Simultaneous topup injection (PPM)

3 rings(LER, HER, PF)

No top-up

Eventually

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

Injector Linac Status

K.Furukawa, ARC2018, Mar.201816

Injector Linac Mission

Mission of Electron/positron Injector in SuperKEKB
v For 40-times higher luminosity in SuperKEKB collider
v Low emittance & low energy spread injection beams with 4 times higher beam current³ New high-current photo-cathode RF gun³ New positron capture section³ Positron damping ring injection/extraction³ Optimized beam optics and correction³ Precise beam orbit control with long-baseline alignment³ Simultaneous top-up injection to DR/HER/LER/PF/PFARv Balanced injection for the both photon science andelementary particle physics experiments
Low emittance
RF-gunDamping
Ringe–Injector Linace+600 m

High efficiency
e+ generator

2x beamcurrent

PF
2.5 GeV

e–e+ BTPF-AR
6.5 GeVe – BT

Beam from Injector and Storage Current
SuperKEKB:
7 GeV e2600 mA
4 GeV e+3600 mA
PF:
2.5 GeV e450 mA
PF-AR:
6.5 GeV e60 mA

HER
7 GeV

SuperKEKB
3 km

LER
4 GeV

Belle II
40xLuminosity

Injector Linac Status

The single injector would behave asmultiple injectors to multiple storagerings by the concept of virtual
accelerator
K.Furukawa, ARC2018, Mar.201817

Injector Linac Overview
uInjector linac configuration

vMajor upgrade items³Photo-cathode RF-gun for low-emittance e³Flux concentrator, LAS structure, solenoids, quads for e+³Pulsed magnets for adequate beam optics for each beam
³High-precision beam position monitor³High-precision beamline alignment for low emittance
Injector Linac Status

K.Furukawa, ARC2018, Mar.201818

Structure of Waveguide Flange
Metal Seal (Vacuum)
RF Contactor (Electric)

Emphasized figures

Correct

only 150 µm difference
Injector Linac Status

Wrong
K.Furukawa, ARC2018, Mar.201819