Overview of Injector Linac
Kazuro Furukawa
for Injector Linac

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

Linac Overview

Mission of electron/positron Injector in SuperKEKB!!40-times higher Luminosity"!Twice larger storage beam
# Higher beam current at Linac"!20-times higher collision rate with nano-beam scheme$!# Low-emittance even at first turn$!# Shorter storage lifetime# Low-emittance beam from Linac# Higher Linac beam current!!Linac challenges"!Low emittance e$!with high-charge RF-gun"!Low emittance e+$!with damping ring"!Higher e+ beam current$!with new capture section"!Emittance preservation$!with precise beam control"!4+1 ring simultaneous injection
Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

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Linac Upgrade for SuperKEKB!! Higher Injection Beam Current"! To Meet the larger stored beam current and shorter beam lifetime in the ringIr5Ce"! 4~8-times larger bunch current for electron and positron!! Lower-emittance Injection Beam"! To meet nano-beam scheme in the ring"! Positron with a damping ring, Electron with a photo-cathode RF gun"! Emittance preservation by alignment and beam instrumentation!! Quasi-simultaneous injections into 4 storage rings (PPM)"! SuperKEKB e–/e+ rings, and light sources of PF and PF-AR"! Improvements to beam instrumentation, low-level RF, controls, timing, etc

SuperKEKB injector Linachihigh currentgun

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

S-bandlinac

e+ target &L-band+LAS
capture section
Linac Upgrade Status towards SuperKEKB

1.1 GeV
Damping Ringcirc. 136 m
Energy-spread
Compression System
3TRF gunFC

50 Hz (e+ or e-)pulse-by-pulse
mode switching PFPF-AR
LER 6.5 GeV e-

2.5 GeV e0.1nC x 1

4.0 GeV e+ 4nC x 2ECSECS
SC-bandmodules

HER 7.0 GeV e-5nC x 2K.F, KEK, Mar.2014.

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Fire during flux concentrator development!!One of small problems – Cables burned by 20cm

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

4

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

Linac Schedule Overview

e- commiss.
at A,B,J,C,1
Qe- = 5nCe+ 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 dad e+ cos.
s
at 1,2, 3,4,5 sectors
e- commiss. at A→5 sectors

4 nC

2 nC

ped e+ commisscommiss.
a
at 1→5 Qe+ = 1~4nC
e- commiss.
at A→5 Qe- = 1~5nC

PF-AR ecommiss.

K.F, KEK, Mar.2014.

5Several Workshop around Injector Linac!!Technology choice for beam position monitor (BPM)"! Indispensable for emittance preservation"! ~10µm precision (~100µm in KEKB project), about 100 BPMs, event-based controls"! Review by experts from SLAC, Steve Smith and Andrew Young"! Many valuable discussions on filter design, digital signal processing, etc.
"! One of the developments was chosen for performance, operation, and budget!!Laser and photo-cathode RF gun workshop"! 6 presentations, 16 participants"! The same objectives of low emittance and higher stability"! Injector linac is unique on higher beam charge with lower energy spread"! Should exchange technology/information continuously!!Accelerator structure processing workshop"! 22 participants"! Many discussions on duration (more than a month), and the system"! No baking necessary, longer processing and better monitors, better interlock needed
Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

6

SuperKEKB Workshop (Nov.2013)!! PEDD dependent on beam repetition?
"! SLAC study was on single-pulse energy density$! may need further investigation!! Fiber loss monitor blackening around target?
"! Can be replaced routinely!! Diamond loss detector?
"! Is worth comparing in the future!! Orbit stability tolerance against beam size?
"! Pinhole 2mm and beam sigma 0.3mm are possible
Beam orbit jitter will be studied, as well as for emittance preservation!! Rotating target/spoiler?
"! Should be studied for the beam current larger!! Frequency synchronization btw. linac/ring?
"! All SKEKB frequencies are generated from common freq. with ring circumference compensation!! Beam charge variation pulse-pulse?
"! Can be important"! Technically possible with different event assignment"! Means different injection modes with different orbit stabilization for wakefield!! Target quad – pulsed ?
!! Beam jitter should be small!! DR extraction angle jitter"! Offset injection position/angle jitter should be small
Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

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Photo-cathode RF-gun Development!!A1 RF-gun (GR_A1) under test"!Big progresses are quasi-traveling wave sidecoupled cavity, Ir5Ce photo-cathode, Yb fiber laser"!Should understand those many new components forreal stable operation"!5-nC per bunch was re-confirmed with newconfiguration"!600-m transport was confirmed (with small charge)"!Longitudinal laser pulse manipulation is necessaryfor energy-spread and stability management

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

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Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

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Positron Source!!High current positron is required!!Positron capturing with flux concentrator (FC)and large aperture s-band structure (LAS)!!Deceleration field to reduce satellite bunches!!Pinhole beside target for electron beam!!Protection system with beam spoilers

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

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Flux Concentrator Assembly
FC assembly

primarye- beam

positronproduction
Targetquickkd
detachable power & water connection
to minimize worker's radiation dose
FluxConcentrator
BridgeCoilse+ beam
Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

12

Improved beam optics design!!Pulsed quad addition – Simultaneous injection!!FODO → Doublet – Emittance preservation!!Orbit correction simulation!!Further emittance preservation even withalignment tolerances!!Optimization of installation scheme foravailable budget

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

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Energy profiles and beam properties"

1.5 GeV e-#

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

!

$

%

!"#$%&'!$#)*%! e-/e+ beams are delivered to 4-rings withdifferent current & energy.
%! "+/23/,,+-+./7843289+132:103;+31<=0,>+93;63(?3@A3B:-1+C;6CB:-1+3D8.308BC:B3=4E+,784F

&'!()*+,-%.!

/0123#4!5#

1/2+3+4+.56()+,+-+./0+e-
1.1 GeV!"#$%&'!$# e+

@G*H3I3J+K3+C33
(34#3Q%
!*H3LF(3J+K3+C
?F&34#3Q$

OG*H3%F(3J+K3+P
'34#3Q%
MNH3%F(3J+K3+C
?F&34#3Q$

206#4!5##$%&'(

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

K.F, KEK, Mar.2014.

Emittance Preservation!!Offset injection may solve the issue!!Orbit have to be maintained precisely
Mis-alignment leads to Emittance blow-up

Orbit manipulation compensates it

100 samplesSugimoto et al.
Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

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

Event-based
Control SystemEvery
20 ms

F.B
e! Gunn
ARC

F.B

PF Injectione– ((2.5GeV,2 5G V 0
2.5GeV
0.2nC)
2F.B
e! GunARC

Damrringing

SuperKEKB-LER Injection

F.B

e– (3.5GeV, 10nC)

F.B

eargete+ (4(4GeV,4GeV 44nC)nC)

e! GunARC

SuperKEKB-HER Injection

F.B
e! GunARC

PF-AR Injection

F.B

e– (7GeV, 5nC)
F.B
e– (6(6.5G
6.5G
65G

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

5nC)
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Instrumentation!!RF stability is crucial for the beam"!LLRF monitor is being developed"!60 high-power klystrons and 10 middle-powersystems"!50Hz synchronized data acquisition with event(beam-mode) recognition"!0.1% amplitude and0.1degree phase resolution

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

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Presentations for Injector Linac!!Injector commissioning!40'"!Speaker: Masanori!Satoh!(KEK)!!RF gun and emittance preservation!40'"!Speaker: Mitsuhiro Yoshida!(KEK)!!Positron source!30'"!Speaker: Takuya!Kamitani!(KEK)!!Timing synchronization!20'"!Speaker: Hiroshi!Kaji!(KEK)!!LLRF development!20'"!Speaker: Takako!Miura!(KEK)

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

21

Summary!!Steady progress towards first MR injection in 2015!!Will finish earthquake disaster recovery in 2014!!Will make staged improvements before 2017!!Will balance between final beam quality andstable/staged operation!!Will select optimized route depending on availableresources

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

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Mt. Tsukuba

Thank you
SuperKEKB
dual rings
PF-ARPF

Linac Upgrade Status towards SuperKEKB

Injector
Linac

K.F, KEK, Mar.2014.

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Linac Upgrade Status towards SuperKEKB

K.F, KEK, Mar.2014.

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