Progress of Injector Linac
Kazuro Furukawa
for Injector Linac

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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Linac Overview

Mission of electron/positron Injector in SuperKEKBu 40-times higher LuminosityvTwice larger storage beamà Higher beam current at Linacv20-times higher collision rate with nano-beam scheme³ à Low-emittance even at first turn³ à Shorter storage lifetimeà Low-emittance beam from Linac
à Higher Linac beam currentuLinac challengesvLow emittance e³ with high-charge RF-gunvLow emittance e+³ with damping ringvHigher e+ beam current³ with new capture sectionvEmittance preservation³ with precise beam controlv4+1 ring simultaneous injection
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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8

18000
Operation Time / year [hrs]

16000

7

Total Operation Time [hrs]Machine Failure [%]

14000

6

12000

5

10000

4
8000

3

6000

Machine Failure [%]Cumulative Operation Time / 10 [hrs]Operation Time / year [hrs]Injector Linac Operational History

2

4000

1

2000
PF	

KEKB	

TRISTAN	

1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013

0

FY
Linac Upgrade Status towards SuperKEKB

0Earthquake
K.Furukawa, KEK, Nov.2014.

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Operation StatisticsuFY2013 StatisticsvOperation time: 5315 hours (FY2012 -0.3%)³PF/PF-AR Injection and Commissioning for SuperKEKBvFailure rate: 0.43% (FY2012 -0.87 point)³Failures include stand-by devices³Not all of failures affected the injectionsvFailure rate was the best in these 20 years³Earthquake recovery goes well
³Old devices do not reach their lifetimes yet³Commissioning for SuperKEKB is performed deliberately

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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Positron Generationu4-times more positron is required at
SuperKEKB than KEKBvSafety measure was taken after cable fire during thetest of Flux Concentrator (FC)vNew components in
100-m capture section
were tested in stepsvHigh voltage tests intunnel in AprilvBeam tests with electron
in MayLinac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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6	

Positron generation for SuperKEKB
side	
  view	
10 nC
primary e-	bridge coils	

DC QM	
 spoiler	target	solenoid	
primary
e- beamLAS Accel.
structure	

e+	
 positron
beam
hole	

production
Target

5 nC injection e-	
Flux
Concentrator	

pulsed ST	pulsed QM	

FluxConcentrator
BridgeCoils
e+ beam

New positron capture section after target with
Flux concentrator (FC) and large-aperture S-band structure (LAS)
Satellite bunch (beam loss) elimination with velocity bunching
Pinhole (2mm) for electrons beside target (3.5mm)
Beam spoiler for target protection
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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First Positron Observation from New GeneratoruDevices and primary electron beam studieduFirst positron signal confirmed on Jun.5
uPositrons transferred to the beam dump on Jun.6
uConsistent with simulation designsuExpect design achievement after fullconstructions

Signal fromprimary electron

Linac Upgrade Status towards SuperKEKB

Signal from positronwith opposite polarity

K.Furukawa, KEK, Nov.2014.

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Positron from New Positron Capture Sectionu Generated positron ~0.1nC wastransferred to the entrance of
damping ringu With higher magnetic and electricfield, 4-nC positron will be
generatedu Target shield(40cm x 6m long)
Beam position
will be finalized
Horizontalu Alignment will be
Vertical
improved
3mm à 0.1mm
Beam charge

Linac Upgrade Status towards SuperKEKB

Large
Flux
concentrator
aperture S-bandand structure
beforefollowingsolenoidsolenoid/quad& quad installation

400 m~0.1 nC

PositronPrimary Electron
W target
K.Furukawa, KEK, Nov.2014.

15

T.Kamitani(1) FC current

FC currentがzeroでもある程度のyieldがある

6kAより大きな電流値でもまだsaturationせずに順調に伸びていくと期待される新型電源では12kAまで上がる予定。
snubber回路無しではさらに上がる
可能性あり。

FCでの実電流値は1.07倍
plot上の6kA => 6.42 kA

CT測定値
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

(2) Bridge Coil current

T.Kamitani[1] 650A以上ではほぼ一定。
電源最大値は750A。現在はケーブルの発熱より600A以下で運転している
なお、FC currentに比べて最大到達値が低いのは、このデータの方が早い時期に取られたがその後チューニング
によりyieldが向上したためである。
[2] zero currentではyieldが低い。

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

(3) DC solenoid 1-5 current

T.Kamitani

Yieldがややsaturationの傾向？
FC currentが高くなるとこれももっと向上するかもしれない
本来の電源最大値は650Aであるが電力系の制約より370A以下で運転している。2014年秋以降改善予定

現在のBPMでは0.02nC以下はbackgroundに埋もれて測れないのでyieldも0.06以下はfakeのゲタ。

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

(4) DC solenoid 1-6 current

T.Kamitani

320A付近がoptimumでそれより上では悪化する
FC currentが高くなるとこれももっと向上するかもしれない
本来の電源最大値は650Aであるが電力系の制約より370A以下で運転している。2014年秋以降改善予定

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

T.Kamitani(5) e+ RF phase [1-5と1-6の位相関係は固定]	

FCの広いアクセプタンスのおかげで減速捕獲でもほぼ同じ収量が得られる。
減速捕獲の方が陽電子のバンチ長、エネルギー広がりが小さい。
減速捕獲

加速捕獲

測定値

simulation

シミュレーションに比べて絶対値にはすこしズレがあるが位相依存性についてはよく再現されている。

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

(6) Acc-field grad./phase at 1-5

Linac Upgrade Status towards SuperKEKB

T.Kamitani

K.Furukawa, KEK, Nov.2014.

(6-2) Acc-field grad. [MV/m] at 1-5

T.Kamitani

SLED を使用し、14MV/m 程度まで向上する予定

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

T.Kamitani

Positron Generation

1) Installation of positron generator for SuperKEKB in April 2014
(Beamline construction since summer 2013)(positron target, spoiler, Flux Concentrator, bridge coils, LAS structures [x6], DC solenoids [16+13],
e+/e- separator, quads [>90])

2) Commissioning of positron beam, observation of the first
positron after reconstruction for SuperKEKB, further
improvements expected
Primary e- [nC] Positron [nC]
June 2014
Specification(at SY2)

0.6

0.12

x17

10.0

DR injection(2016?)
3)

Oct.~Dec.2014 : Linac commissioning
Jan.~Mar.2015 : Construction
Jul.~Sep.2015 : Construction

Linac Upgrade Status towards SuperKEKB

5.0
4.0

x42

Efficiency

Parameters

20%

FC 6.4kA, Solenoids 370A,
LAS capture field 10 MV/m

50%
40%

x2.5

FC 12kA, Solenoids 650A,
LAS capture field 14 MV/m
Energy spread acceptance0.5%

Apr.~Jun. : Linac commissioning
Oct. : LER injection
K.Furukawa, KEK, Nov.2014.

Facility for Electric Power and Cooling Wateru Linac needs electricity and cooling water extensions, especially for
positron generator upgrade, that was planned in FY2012u Separate building construction in FY2013 not to impact PF/PF-AR
u Facility extensions performed during summer 2014
SuperKEKB injector	

1.1 GeV
Damping Ringcirc. 136 m	

low emittanceRF gun	
3.5 GeV
10nC x 2 (prim. e-)
5nC x 2 (inj. e-)	Bunch
Compressor	

S-bandlinac	

Energy-spread
Compression System	
3T
RF gun	Linac Upgrade Status towards SuperKEKB

PF

AR

2.5 GeV e- 6.5 GeV e- 	
0.1nC x 1	LER

4.0 GeV e+
4nC x 2	HERe+ target &LAS capture section	
[1] Sector 1,2
Electricity and coolingwater addition for new
positron generator+920 kVA, +900 L/min

50 Hz (e+ or e-)pulse-by-pulse
mode switching 	

ECS	

7.0 GeV e5nC x 2	[2] Sector 2,3
Electricity addition for
new damping ring
+310 kVA[3] Sector 5Electricity and cooling water
addition for energy compression,
beam diag., injection beamlines+300 kVA, +460L/min
K.Furukawa, KEK, Nov.2014.

Photo cathode RF gun development

Cascaded frequency doublers
Quasi traveling wave side couple cavity
Yb fiber and Yb:YAG think disk laser

Ir5Ce
CathodeIr5Ce photo cathode
Linac Upgrade Status towards SuperKEKB

u 5.6 nC / bunch was confirmedu Next step: 50-Hz beam generation &Radiation control
K.Furukawa, KEK, Nov.2014.

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Photo cathode RF gun improvementuCrucial for high-current low-emmittance beamuNew Ir5Ce cathode and new cavity QTWSC weresuccessfuluBasic features were confirmed at 2 ~ 5 HzuExpect beam parameter and stability performanceat 50 HzuStaged laser system improvements with beammeasurementsuRegenerative amplifiers were replaced with multipass amplifiers for their heat to achieve 25 Hzthen 50 Hz
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

26

Emittance Preservation and Alignmentu If Device is off center of the beamv Focusing magnet (quad) kicks the beam bunchv Accelerating structure (cavity) excites wakefield, to bend the tailu Distorted bunch in banana shapev Emittance dilution or blow-up, even 100 times larger³ Depending on the beam optics and the beam chargeu Alignment and orbit correction is crucial to preserve theemittance
Sugimoto et al.

Beam
Focusing
MagnetAccelerating
Structure
Transverse beam distribution in time direction

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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Emittance Preservationu Offset injection may solve the issueu Orbit have to be maintained preciselyu Mis-alignment should be <0.1mm locally, <0.3mm globally
Mis-alignment leads to Emittance blow-up

Orbit manipulation compensates it

100 samples
Sugimoto et al.
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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Alignmentu High-precision alignment was not necessary in PF and KEKB
injections, and it was much damaged by earthquake in 2011.
u Instead of flexible-structure girder before earthquake, rigidstructure was adopted with jack-volts and fixed supports.
u Reflector pedestals are mounted onto quad magnets andaccelerating cavities for laser-tracker measurement.
u Iterative measurement and adjustment with 500-m straight laser
and position sensors should enable 0.3-mm global alignment.
u Laser tracker should enable 0.1-mm measurement within 10-m
girder unit.
u Displacement gauges, hydrostatic leveling, inclinometer are also
employed.
u Remote measurement system and girder mover system will benecessary for longer term, and are under development.
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

29

Alignment work at summer 2014u For the first time at 3-5 sectorsu Horizontal axis: sensor number from sector C, 1-4, to sector 5 (~80m/sector)u Vertical axis: voltage (~displacement at 0.25~0.5mm/V)u Some girders were not yet upgradedu Moved up to 3 mm not to break vaccuum

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

30

Alignment work during summer 2014u Several measurements during summeru Measurement reproducibility was confirmed up to ~0.2mmu While there existed
many conflicting
measurements,
consistent scheme
has been establishedu Movement of tunnel
by several 10’s of
micrometer wasobserved (→ mover)
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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InstrumentationuRF stability is crucial for the beamvLLRF monitor is being developedv60 high-power klystrons and 10 middle-power systemsv50Hz synchronized data acquisition with event (beammode) recognitionv0.1% amplitude and0.1degree phase resolutionuBPM precision improvementv100μm à 50μm à < 10μmvEvent recognitionvMass production is underwayuOther beam monitors
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

32

Staged Radiation Control License towards SuperKEKB

uTwo licenses were approved in June 2014u[1] Beam diagnostic station at #A2 just after gunvfor 1250nC/s at 50Hz 2bunchesu[2] Beam dump at #28 just before damping ringvfor 10nC/s with positronsuRadiation measurements especially at positron
generatorvIndispensable to estimate radiation at >100 times higher beamuBoth approveduSoon apply for the next license at ~May.2015

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

33

Linac Schedule Overview (as of Mar.2014)

RF-Gun e- beamcommissioning
at A,B-sector
Qe- = 5nC

e- commiss.
at A,B,J,C,1
Qe- = 5nC

e+ commiss.
at 1,2 Qe+ = 0.5nC (FC, DCS, Qe- 50%)e- commiss.
at 1,2,3,4,5 Qe- = 5nC

1 nC: Electron: Positron: Low current electron

Linac Upgrade Status towards SuperKEKB

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

4 nC

2 nC

damped e+ commiss.
at 1→5 Qe+ = 1~4nC
e- commiss.
at A→5 Qe- = 1~5nC

PF-AR ecommiss.

K.Furukawa, KEK, Nov.2014.

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RF-Gun e- beamcommissioning
at A,B-sector
Qe- = 5nC

Linac Schedule Overview (Newer)
e- commiss.
at A,B,J,C,1
Qe- = 5nC

e+ commiss.
at 1,2 Qe+ = 0.5nC (FC, DCS, Qe- 50%)e- commiss.
at 1,2,3,4,5 Qe- = 5nC

1 nC: Electron: Positron: Low current electron

Linac Upgrade Status towards SuperKEKB

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

4 nC

2 nC

damped e+ commiss.
at 1→5 Qe+ = 1~4nC
e- commiss.
at A→5 Qe- = 1~5nC

PF-AR ecommiss.

K.Furukawa, KEK, Nov.2014.

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SummaryuSteady progress towards first MR injection in 2015
uWill finish earthquake disaster recovery in 2014uWill make staged improvements before 2017uWill balance between final beam quality andstable/staged operationuWill select optimized route depending on available
resources

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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Mt. Tsukuba

Thank you
SuperKEKB
dual rings
PF-AR
PF

Linac Upgrade Status towards SuperKEKB

Injector
Linac

K.Furukawa, KEK, Nov.2014.

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Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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Positron SourceuHigh current positron is requireduPositron capturing with flux concentrator (FC)and large aperture s-band structure (LAS)uDeceleration field to reduce satellite bunchesuPinhole beside target for electron beamuProtection system with beam spoilers

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

40

Flux Concentrator Assembly
FC assembly

primary
e- beampositronproduction
Targetquick detachable power & water connection
to minimize worker's radiation dose
Flux
Concentrator
BridgeCoils
e+ beam
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

42

Energy profiles and beam propertiesB	

1.5 GeV e-	C	

10 nC x 2 (for LER)
5 nC x 2 (for HER)
0.3 nC x 1 (for AR)
0.3 nC x 1 (for PF) 	
low emittance
1.1 GeV
RF gun	

A	

1	

2	

e+	
  target	
  	

same	
  energy	DR	l e-/e+ beams are delivered to 4-rings withdifferent current & energy.
l Beam	  accelera;on	
  modes	  must	  be	
  switched	
  by	
  
50	
  Hz	
  pulse-­‐by-­‐pulse	
  for	
  top-­‐up	
  injec;on.	

3	

4	

5	

e-­‐:Chicane	

4.219	
  GeV	
  e-	Decelerate	

1.1 GeVe+	
  target	
  	
 e+	

HER:	
  7	
  GeV	  e-­‐	
  	
  	
5	
  nC	
  x2	
AR:	
  6.5	
  GeV	  e-­‐	
0.3	
  nC	
  x1	

LER:	
  2.5	
  GeV	
  e+	
4	
  nC	
  x2	
PF:	
  2.5	
  GeV	  e-­‐	
0.3	
  nC	
  x1	

1.5	
  GeV	
  

C	

1	

2	

3	

4	

5	

Beam optics should satisfy the fast beam-mode switching.	
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

Pulse-to-pulse modulationu Four PPM virtual accelerators
for SuperKEKB projectmaybe withadditional PPM VAs
for stealth beammeasurements
based onDual-tier controls withEPICS and event-system

Event-based
Control System

Every
20 ms

F.B
e− GunARC

F.B

PF Injectione– (2.5GeV, 0.2nC)

F.B
e− GunARC

Damping ring

SuperKEKB-LER Injection

F.B

e– (3.5GeV, 10nC)

F.B

e+ Targete+ (4GeV, 4nC)

e− GunARC

SuperKEKB-HER Injection

F.B

e– (7GeV, 5nC)
e− GunARC

F.B

PF-AR Injection

F.B
e– (6.5GeV, 5nC)

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Nov.2014.

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