Present Status ofInjector Linac and Damping Ring
Kazuro Furukawa
for injector linac and damping ring, KEKInjector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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Linac upgrade overview

Mission of electron/positron Injector Complex in SuperKEKB

u40-times higher Luminosity
v20-times higher collision rate with nano-beam scheme³ à Low-emittance even at first turn³ à Shorter storage lifetime

vTwice larger storage beam

à Low-emittance beam from Injector
à Higher beam current from Injector

uInjector challenges
vLow emittance e³ with high-charge RF-gun

vLow emittance e+³ with damping ringvHigher e+ beam current³ with new capture section and BTsvEmittance preservation³ with precise alignment & beam control

v4+1 ring simultaneous injection
Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

2Required injector beam parametersStage

KEKB (final)

Beame+e–e+e–e+e–Energy

3.5 GeV

8.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeVStored current

1.6 A

1.1 A

1A

1A

3.6 A

2.6 A

Life time

150 min.

200 min.

100 min.

100 min.

6 min.

6 min.

Primary e-10nC

Present Phase-I

Primary e- 8nC

Bunch charge→ 1 nC

1 nC→ 0.4 nC

Norm. Emittance(gbe) (µrad)

2100

200

2400

Energy spread

0.125%

0.125%

No. of Bunch / Pulse

22Repetition rate

50 Hz

Simultaneous top-up
injection (PPM)

3 rings(KEKB e–/e+, PF)

Injector Linac and Damping Ring towards SuperKEKB

1 nC

SuperKEKB (final)

Primary e-10nC→ 4 nC

5 nC

150

100/20(Hor./Ver.)

50/20(Hor./Ver.)

0.5%

0.5%

0.1%

0.1%

2222

25 / 50 Hz

50 Hz

No top-up

4+1 rings(SuperKEKB e–/e+, DR,PF, PF-AR)
K.Furukawa, KEK, Jun.2016, B2GM.

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Progressu2010: Beam design and hardware developments
u2011-2014: Recovery from earthquake, mainly
because of soft-structure girder designu2012-: Linac construction and commissioningu2012-: Step-by-step acquirement of beam licenses
u2016: Phase-1
u2017: Damping ring commissioning, Phase-2
uContinuous: Light source injectionsu…

Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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Linac Upgrade Overview

Linac Upgrade Progress towards SuperKEKB (1)u High-charge low-emittance RF gun development
v QTWSC cavity and Ir5Ce photo cathodedevelopments
v Laser development is underway

Quasi traveling wave
side couple cavity

Ir5CeCathodeu Positron generator commissioning
Positron generator

v Good agreement with the simulation resultsv Will solve discharge issues

u Precise alignment for emittance preservation
v Recovering after large earthquake in 2011v Reaching specification of 0.1~0.3mm
v Longer term stability should be solvedu Utility upgrade during FY2014
v for electricity (+1.5MW) and cooling water (+1400L/min)
Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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Linac Upgrade Overview

Linac Upgrade Progress towards SuperKEKB (2)u High-power microwave modulator upgradesu Low-level RF controls/monitor upgrades
v Pulse-to-pulse modulation (PPM) between 4+1 rings
v More spaces for increased number of devices

u Beam instrumentationv Large/small aperture beam position monitors (BPM)v Precise/fast and synchronized BPM readout systemv Wire scanners and beam loss monitors
v Streak camerasv (Deflectors, etc.)

u Pulsed magnet developments
v ~3 bends, ~30 quads, ~40 steerings
v Even with energy recovery

u Event-based control and timing system upgrades
v Combination of MRF & SINAP modules
v Essential for PPM operationv Precise timing & synchronized controlsv Bucket selection at DR and MR
Injector Linac and Damping Ring towards SuperKEKB

Pulse magnet tests

SINAP event modules

Beam wire scanner

K.Furukawa, KEK, Jun.2016, B2GM.

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FC test stand (2015 July)n test operation performed withu spare FC-base (#4)
u 12-kA pulse modulator
u new coaxial cables
u new triplate feeder line
u snubber circuit
u but w/o bridge coils
n full-spec (12 kA) operation forcontinuous 200 hours achieved with noserious breakdowns and problems

triplate
feeder line
snubbercircuit
FC-base (#4)

coaxialcables

cable connection
inside modulator
Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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FC assembly #2 & test standu Operation test with BC field isessential.
u FC assembly #1 is radio-activated in
the beam line.
u Construct assembly #2 for operation
with BC field at test stand.
u Test-1: operation with FC-head #4(not work-hardened model) to see
what happens in the same situation
as the damaged FC.
[2016 June, soon]u Test-2: operation with FC-head #5(well work-hardened model) to checkthe operability at full current (12 kA)
under the BC field.
[2016 August ~]Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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DR layout

Damping Ring System Layout

M. Kikuchi

1.5%

Energycompression

5%
Collimators in the arc
20% is cut at tailInjector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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DR layout

Damping Ring Beam Parameters

M. Kikuchi

LinacLTRDRInjector Linac and Damping Ring towards SuperKEKB

RTLK.Furukawa, KEK, Jun.2016, B2GM.

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DR construction

Hardware Status

M. Kikuchi•LTR / RTL beam transport lines• Magnet: Installation completed• vac. chamber:• installation, beam instrumentation in 2016 / 2017
•DR
• Magnet: Installation completed (except for steerings in the straight)• Vacuum chamber: installation is underway
DampingRing

Extractionline

DR and the extraction line

Installation of vac. chambers• Power supplies for the magnets:• All delivered. Tuning will be done in 2017.
• Steering PS will be delivered in 2017.
Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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DR construction

M. Kikuchi• Beam instrumentation:• Most of sensors, electronics and cables delivered.
• Cabling of BPM completed in FY2015.
• Kicker system for injection/extraction:• Magnets and the power supplies are delivered.
• Double half-sine pulse for the two bunches• No ringing after pulse

Pulse shape of the kickers.

• Septum magnets for injection/extraction:• Magnets and pulsers are delivered.
Septum magnet for injection.

• Two RF cavities were fabricated.
•installed in the tunnel in June 2016.
Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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DR timing

Bucket selection in Phase-2 with DRu Without DR, simply wait up to 5120 x 96 ns ~ 490 μsv 96 ns : highest common frequency between linac – ringe− GunKEKB

ARCe+ BT (3.5GeV, 0.6nC)

Primary e– (3.5GeV, 10nC)
e+ Targetu With DR, in order to select arbitrary bucket in MR, have to wait up
to ~4.5 ms, even if a bucket in DR was carefully selectedv Power supply can wait only 2 ms, one of only 2798 buckets in 5120 buckets can beselected, may have to change LLRF condition at latter half of linac every pulse>100nse− GunARC
Primary e– (3.5GeV, 10nC)

96ns

e+ DR (1.1 GeV, 4nC)

>100ns
96ns

SuperKEKB
e+ BT (KEKB: 4GeV, 4nC)

e+ Targetv Can be a big challenge in LLRF precision
Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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DR schedule

Construction Schedule

Injector Linac and Damping Ring towards SuperKEKB

M. Kikuchi

K.Furukawa, KEK, Jun.2016, B2GM.

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Schedule

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

Linac Schedule Overview

e- commiss.
at A,B,J,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↓BeamLow

Licenses

Emittancein stepsBeams

4+1 Ring
InjectionsDRCommiss.
1 nC

2 nC

4 nCPhase1

Phase2Phase3

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

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

Injector Linac and Damping Ring towards SuperKEKB

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

K.Furukawa, KEK, Jun.2016, B2GM.

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Injector Beam Commissioning for Phase-1
u Electron beamv Thermionic gun
at the beginningv 1 nC per bunchv 2 bunches per pulse
v 50 pulse per secondu Positron beamv Primary electronwith 7-8 nC per bunchv Positron of 0.7 nC
at linac end
without damping ring

Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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Beam from RF gun

Progress: RF gun
u MR injection from RF gun during Phase-1 was recommended in thelast gun review, and was planned for May 2016 since the last yearu On May 31, even an unusual centipede (~15cm!!) managed to visit
the operation room to celebrate the first injection into HER

Ibaraki Nature Museum

Injector Linac and Damping Ring towards SuperKEKBK.Furukawa, KEK, Jun.2016, B2GM.

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Beam from RF gun

Beam from RF gun
u Successful Injection into MR for the first time, on May.31
u And continuing the RF gun operation since Jun.8

Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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Beam from RF gun

Wire Scanner Measurementu Present beam: 1nC/bunch, 25Hz, 20mm.mrad at the gun,30~200 mm.mrad at the linac end, ? Energy spreadu Phase-2: 2nC/bunch, 50Hz, 20 mm.mrad at the linac end, 0.1% energy spreadu Phase-3: 4-5nC/bunchu Much room to enjoy the improvements
Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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SummarySummaryu Injection into SuperKEKB is another challenge with higher beam
charge and lower transverse and longitudinal emittanceu Steady progress towards designed injection beam in steps
v Alignment: almost confident on the required precision (0.1-mm local, 0.3-mmglobal), need to maintain for longer termv Positron generator: another license test, need discharge analysis
v Thermionic gun: re-commissioned for primary electron for positron generationv RF gun: successful HER injection, following recommendations at review meetingsv Need more radiation shieldv Need much construction left for 2017u Will balance between final beam quality and progressive operationu Will select optimized route depending on available resourcesv Negotiation with light sources
v Commissioning and development in parallel (no other choices)

Injector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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Mt. Tsukuba

Thank you
SuperKEKBdual rings
PF-ARPF

600m Injector
LinacInjector Linac and Damping Ring towards SuperKEKB

K.Furukawa, KEK, Jun.2016, B2GM.

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