Introduction to
the Electron/Positron Injector LINAC

Kazuro Furukawa for Injector LINAC<http://www-linac.kek.jp/linac-paper/general/>< kazuro.furukawa@kek.jp >Introduction to Injector LINAC

K.Furukawa, Jan.2024

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uHistory
uKEKB
uSuperKEKB
uComponents
uUpgrade

Introduction to Injector LINAC

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42-year History

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Injector Linac Project History
1980
1990
2000
2010
2020
JFY 1970
Exp. Energy 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3

Project

Injection Energy

Photon Factory

2.5 GeV

2.5 GeV

TRISTAN

2.5 GeV

32 GeV

Injection Operation

Construct.
Construct.

Slow Positron 2.5 GeV - 55 MeV 0.1 - 35 keV
KEKB
PF-AR
SuperKEKB

8 / 3.5 GeV

8 / 3.5 GeV

Injection Operation
Operation
Construct.

Operation
Injection Operation

2.5 GeV - 6.5 GeV 5 - 6.5 GeV
7 / 4 GeV

Injection Operation

7 / 4 GeV

Construction
TRISTAN32 GeV/cu 42 years of operation

1986 – 1994

AR
8 GeV/cv for particle physics and photon science³ Started with one of first dedicated light sources, PF³ and the highest energy collider, TRISTAN with SRF

Injectione- BT

Linac delivered:for PF: 2.5 GeV e–
for TRISTAN:
2.5 GeV e–
2.5 GeV e+
e+, e- Linac

PF
KEKB

Belle

v Long-term multiple disciplinary operations
v Still many devices from the first generation

2.5 GeV/c

HER
8 GeV/c

1999 – 2010

PF-AR
6.5 GeV/c
e- BT

Linac delivered:for PF:
2.5 GeV e–
for PF-AR: 3 GeV e–
for KEKB: 8 GeV e–
3.5 GeV e+
e+, e- Linac

e+ BT
LER
3.5 GeV/c
PF

2.5 GeV/c

40x
Luminosity

2016 –

Belle II

LER
4 GeV
SuperKEKB
3 km

HER
7 GeV

PF-AR
6.5 GeV

Injection Beam and Storage Current
SuperKEKB: 7 GeV e2600 mA
4 GeV e+3600 mAPF:
2.5 GeV e
450 mAPF-AR:
6.5 / 5.0 GeV e- 60 mAe– BTe +, e –e+ BTHigh efficiency
e+ generator

Injector Linac

Introduction to Injector LINAC

2x beamcurrent

PF
2.5 GeV

700 m

Damping
K.Furukawa, Jan.2024
Ring

4

Low emittance
RF-gunOperation Hours
uYearly operation hours³200,000 hours accumulated on May.7.2020
Statistics of the Injector Linac Operation
8,000

8TRISTAN

KEKB

7,000

SuperKEKB
Operation hourPartial failure

6,000

7

6

5,000

5

4,000

4

3,000

3

2,000

2

1,000

1

0

Rates (%)

Operation (hour)

Injection stop01982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020 2022

Fiscal year
Introduction to Injector LINAC

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KEKB and Linac

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Some of KEKB Designs
uMaximum reuse of TRISTAN inheritanceuHowever, still many improvements applied, ex.
vMany bunch collisions with dual ring collider³Energy asymmetry for the boost of center of mass of Bs

vFull energy injection³Energy upgrade with SLED RF pulse compressor at Linac
w from 2.5 GeV (400 m) → 8 GeV (600 m)

vInjection timing aperture of 30 ps³Slight RF frequency modification to have an integer relation
w Linac 2856 MHz
w Ring (508.5 MHz →) 508.9 MHz

Introduction to Injector LINAC: 10.386 MHz x 275: 10.386 MHz x 49

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PEP-II/SLAC and KEKBuWe exchanged ideas for PEP-II and KEKB
vViewed each other from control rooms

Plots as of Oct.2005³Friendly competition
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Energy and Orbit Stabilization Loops
u BPMs - Energy knob
v Energy knob, freefrom energy spreadv Simple
P.I.
Loop

Many feedback loops along Linac depending on the beam modes

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Feedback loop monitor
u Robust operation
is essential
v Remote monitoring insummary panelv Several conditions,limits in loop
variablesv Beam-mode
dependent operationv Status and variable
logging, and theirviewers

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Two Bunches in a PulseuIn order to double the injection beamuEnergy equalization
vwith beam loading compensation
for bunch separation of 96 ns³We sometimes utilize
energy difference
in order to equalize
the beam orbits

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Continuous injectionua
2004, after continuous injection was applied
Data acquisition continued during injection(8-hour history of beam current, luminosity, etc.)

2003, before continuous injection was applied
Data acquisition stopped during injection(8-hour history of beam current, luminosity, etc.)

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Beam mode switching improvements
uContinuous injection was applied in 2004
Beam mode switching
80000
70000
60000

Count

50000
40000
30000
20000
10000
0
1998

1999

2000

2001

2002

2003
Year

2004

2005

2006

2007

2008

uSwitched 360 times / day in 2008 (every 4 minute)uSimultaneous top-up injection was applied in 2009
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KEKB

Main features of controls at KEKBuEPICS as Main control Software Toolkit
vProvided a robust basis of equipment controls
vReduced software design efforts

uScripting Languages for Operational SoftwarevSADscript/Tk, Python/Tk, Tcl/Tk, etc.
³Especially, SADscript as a bridge btw. Accelerator simulation,
Numeric manipulation, Graphic interface and EPICS controls

vBright new idea in the morning meeting could make theoperation much advanced in the evening³Great tool to optimize the operation by rapid prototyping

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KEKB Operation Improvement (base of SuperKEKB)
red: beam current (e-, e+)purple: vacuum (e-, e+)yellow: luminosity
green: integrated luminosity

Belle/KEK

May.2000
Apr.2003
Dual Bunch e+
Feb.2005
Continuous
Injections
Dec.2008
Crab Cavities andSimultaneous Top-up Injection
Introduction to Injector LINAC

Keeps world
luminosity record
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Linac Design for SuperKEKB

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Linac Overview

Mission of electron/positron Injector in SuperKEKB
u 30-times higher Luminosity
v15-times higher collision rate with nano-beam scheme³ à Low-emittance even at first turn

à Low-emittance beam from Linac

vTwice larger storage beam
³ à Shorter storage lifetime

à Higher beam current from Linac

uLinac challenges

Low emittance
RF-gunvLow emittance e³ with high-charge RF-gun

Damping
Ringe–

Injector Linac

vLow emittance e+³ with damping ring

e+

700 m

High efficiency
e+ generator

2x beamcurrent

PF
2.5 GeV

e–

e+ BT

PF-AR
6.5 GeVe – BTvHigher e+ beam current³ with new capture section

vEmittance preservation

Beam from Injector and Storage Current
SuperKEKB:
7 GeV e2000 mA
4 GeV e+2800 mAPF:
2.5 GeV e450 mA
PF-AR:
6.5 GeV e60 mA³ with precise beam control

v4+1 ring simultaneous injection
Introduction to Injector LINAC

HER
7 GeV

SuperKEKB
3 km

LER
4 GeV

Belle II
30x
Luminosity

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Linac Beam Property Requirements

Linac Beam Parameters for KEKB/SuperKEKB
Stage

KEKB (final)

Beam

e+

e–

e+

e–

e+

e–

e+

e–

e+

e–

EnergyStoredcurrent
Life time(min.)

3.5 GeV

8.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeV

1.6 A

1.1 A

1.0 A

1.0 A

–

–

1.8 A

1.3 A

2.8 A

2.0 A

150

200

100

100

–

–

–

–

6

6

primary e- 10

Bunch charge
(nC)
Norm.
Emittance

Phase-II (achieved)

310

1

→ 0.4

1000

Phase-III (final)

primary e- 100.5

1200/401400

Phase-III (interim)

primary e- 81→1

Phase-I (achieved)

130(gbe) (mrad)

2

2

4

150/30100/40100/1540/20(Hor./Ver.)(Hor./Ver.)(Hor./Ver.)(Hor./Ver.)→4150(Hor./Ver.)

Energyspread

0.13%

0.13%

0.50%

0.50%

0.16%

0.10%

0.16%

0.10%

0.16%

0.07%

Bunch / Pulse

2

2

2

2

2

2

2

2

2

2

Repetition
rate

50 Hz

25 Hz

25 Hz

Simultaneous
top-upinjection(PPM)

3 rings(LER, HER, PF)

No top-up

Partially

50 Hz

50 Hz

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

u Gradual improvements keeping light source injections
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SuperKEKB

SuperKEKB ControlsuInherit Good part of KEKB Controls
vEPICS
vScripting languages

uEPICS Channel Access (CA) EverywherevEmbed EPICS control software (IOC) everywhere
possiblevReduce efforts on protocol design, testing, etc

uDual Tier: Another layer in addition to EPICS/CA
vEvent system helps EPICS with another channel/layervAdditional functionality, synchronization and speed
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Dual-layer Controls

Dual-tier Controls
uIOC controls via Conventional EPICS CA³Above 1ms, ordered controls

uFast FPGA controls via SFP/Fiber (MRF)³10ps ~ 100ms, 114MHz synchronous controls
OPI
Channel Access

IOC

IOC

IOC

IOC

EVG

EVR

EVR

EVR

FPGA/SFP
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Some of Important Components

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RF gunhttps://www-linac.kek.jp/linac-com/rf-gun/Introduction to Injector LINAC

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Photo cathode RF gun development
u Crucial for high-current low-emmittance beamu New Ir5Ce cathode and new cavity QTWSC were successful
u Basic features were confirmed
u Cavity: DAW (disk and washer) à QTWSC (high space charge)u Cathode: LaB6 à Ir5Ce (long life, medium q.e. >10-4)
u Laser: Nd:YAG à Yb:YAG thin disk and fiber à stay at Nd:YAG
Regenerative amp. à Multi-pass amp. w/ coolingu Staged laser system improvements with beam measurements
v Aimed at 5-nC low-emittance stable beam for electron injectionv 50Hz generation with heat dissipation (several possible plans)v Stability improvement, with precise synchronization (commercial oscillator)v Temporal manipulation for lower energy spread (was given up for now)u More stability, more charge, and energy spread mitigation
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RF Gunu DOE diffraction optical elementu 2nd Laser systemu Stability feedback systems
u Yearly replacement of cathodeM. Yoshidan Beam stability improved, but
n Further improvement necessary

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Electron Beamu Transverse and longitudinal emittance blow-up
mitigation should be solvedu High-power square-shaped laser is not stable yet, ECS
is neededvPlan to construct in 2024-2026

u Transverse emittance should be controlled with moreorbit stabilization and residual dispersion function
hunting
u 1.5 nC is acceptable, but still 4 nC - 0.07%(ΔE) was notconfirmed, hope to be investigatedu Emittance blowup in beam transport line by ISR, CSR,
and others is being attacked beforehand
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Positron Generation
https://www-linac.kek.jp/linac-com/positron/

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Positron Generator
DC-gun 10 nC for e+

B

4 nC for e–
A RF-gunFiber & thin disk

J-arclaser, IrCe cathode,
1.5 GeV
Primary e– for e+ QTWSC cavity Bunch
3.2 GeV, 10nC x 2
Compression
Bunch
Compression

C

e+
1 New
2
Capturewith FCPF
2.5 GeV
0.2 nC

1.1 GeV e+damping ring

LER e+
Energy4.0 GeV
Compression 4 nC x 2

EnergyCompression

3

4

Positron target relocation

5

PF-AR
6.5 GeV
0.2 nC

HER
7.0 GeV
4 nC x 2

u Positron energy from 3.5 GeV to 4.0 GeV
v Relocation of target by 40 m with many heavy devices in the capture sectionu Installation of flux concentrator (4 T)
u 1.5 times longer DC solenoid section (0.5 T)
u 100 quad magnets surrounding accelerating structuresu Large aperture S-band structures (LAS) instead of L-bandv L-band structure (5/11 freq. for ILC synergy) and coaxial dummy load weredeveloped as a backup
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28

Positron Enhancement

Positron generation for SuperKEKB
bridge coils

top view
10 nC
primary e-

DC QM

spoilersolenoid
LAS Accel.
structuretargetprimary
e- beame+positronproduction
5 nC injection eTarget

beam
hole

Flux
Concentrator

pulsed ST
pulsed QM

Flux
Concentrator
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)
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After large discharge…
After large discharge

Slit gap got narrow.
Not possible toapply high voltage
unless the gap will
be expanded.
Y. Enomoto, SuperKEKB review, 2019
Introduction to Injector LINAC

e+ source
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Capturing improvementu Cu Ni Alloy was applied for flux concentrator for stable 12 kA
u More beam monitors, more steering magnets are added
0.6

Y. Enomoto
Positron yield● 16_5 12 m downstream from target● 28_4 : Damping Ring

2020b

0.0

2020c

12

0

u 5 nC is available before damping ring now
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Positron Beamu Thermionic gun system is kept for large charge
u FC discharge issue was resolvedu Because of the complicated structure at the capture section
installation of beam monitors and correctors were avoided until
recentlyu Some more beam optimization in the DC solenoid could beapplied, even with more correctors and beam monitors
u 10 – 20% improvement could be achieved with higher gradient of
LAS structuresu Primary electron beam could be increased as in initial plan ofmore than 10 nC (with thermionic gun)u As the present off-center target design is a bit conservative, it
could be optimized moreu >4 nC per bunch can be stably achieved
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Crystal-assisted Positron Generationu Application of electron channeling effect to enhance positron
generationv Experiments at KEK since 2000v Collaboration with LAL/Orsay since 2002 positron yieldv Employed the scheme to enhance KEKB enhancement vs.
crystal angle(mrad)
vs. target
positron injection 30% for a year in 2006
thickness(mm)v Experiments with hybrid crystal andamorphous targets to reduce heat
deposit for linear collider
v Further experiments with granular target
recent experiment forfor cooling efficiency proposed by LAL/Orsay heat/temperature analysis
v Planned to be employed in CLIC and FCC-ee
granular target
hybrid scheme

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Accelerating Structures
https://www-linac.kek.jp/linac-com/6s/

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Acceleration Unit Configuration
Designed performance of the accelerating unit
SLED output
140 MW(mean) 0.5 us

Klystron output
40 MW 4 us

Waveguides~10% power loss

Va = 160 MV (21 MV/m)
for four 2-m structures

Introduction to Injector LINAC

Each unit is 10-m long
60 units are employed
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Accelerator Structureu Approx. 230 S-band accelerating structures employedu Many aged (>40 years-old) structures are degradedv Originally designed for 8 MeV/m and being used for 20 MeV/mv More than 19 structures have discharge issuesv 6 structures had cooling water leakages
v Risk of 7 GeV / 4 GeV acceleration for Υ(4S)
2-m constant gradient structurev Υ(6S) resonance questionable

u New structures are being fabricated and installedv Can reach 30 MeV/mv Since FY2019 as a 5 year plan, 16 structuresv 12 more plannedv Υ(6S) reachable
v But continuous
degradation

Damaged structures
Introduction to Injector LINAC

New design
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Pulsed Magnets / Kickers
https://www-linac.kek.jp/linac-com/pulsed-magnet/

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Pulsed Magnets and Power Supplies for PPM
Y. Enomoto
T. Kamitani

Introduction to Injector LINAC

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Pulsed Magnets
DC Quads

Pulsed Quads

Pulsed Correctors

u Pulsed quad x28 and pulsed corrector x 36 installed in 2017
Now about 100 pulsed magnets
u Many more pulsed magnets are being addedu Good power supply stability of 0.01% (24 hours)u PXI bus, PXI-EVR, cRIO, 50 Hz controls under MRF event and
EPICS
v At first with EPICS/Windows and LabVIEW, and now with EPICS/Linuxu Even with 69% power recovery from coils
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Fast corrector/kicker development
u 2-bunch independent correctorv At the end of Linac (2023) and in BT

u Ceramic embedded coils

T. Kamitani et. al.

Linac endv 2nd bunch can be independently kicked
2nd bunch

1st bunch

Operation
Point

Triggering
Introduction to Injector LINAC

Fast Kicker Duct

Pulsed Power Supply
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Emittance Preservation

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Alignment

Emittance Preservation and Alignmentu If Device is off center of the beam
v 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
the emittance
Sugimoto et al.

Beam
Focusing
MagnetAccelerating
Structure
Transverse beam distribution in time direction

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Alignment

Emittance Preservation
u 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.
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Alignment

Floor vertical movement
in a half year from summer to winter

C3

11

Introduction to Injector LINAC

18

28

38

Higo et al.

48

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Girder mover for structures and magnets, with 1-10 μm precisionu The girder was already developedu The alignment is not a big issue yet at present charge and with BT blowup

Introduction to Injector LINAC

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Energy Spread Management

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RF gun for low-emittance electron

Energy spread reduction using temporal manipulation
M. Yoshida

Energy spread of 0.1% is required for SuperKEKB
synchrotron injection.
15nC

3

t
2.5

5nC10nC

20nC

Gaussian
σE/E (%)

2

1.5

1

t

Square 5nC
10nC

0.5

15nC
20nC

0
0

5

Introduction to Injector LINAC

10 5nC electron
15
FWHM (ps)

20
15nC

25

30

Primary beam for positron production
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uIf the laser shaping is not enough we mayneed to depend on ECS
uEspecially additional requirement of
0.07%(ΔE) is rather difficult

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Positron energy compression system

ECS Chicane

ECS Accelerating Structure

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ECS at MR-BTeu It will be constructed on the BT in 2024-2025.

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Virtual Accelerator
or Pulese-to-pulse Modulation
https://www-linac.kek.jp/cont/epics/event/Introduction to Injector LINAC

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My dream of PPM
u CERN PS Pulse-to-pulse modulation (PPM)v Visit to CERN 1994-1995
v Variety of beams (e-, e+, p, ṕ, HI) every 1.2 (2.4) sec

e-

e-

CERN
Courier
1999
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Dual-layer Controls

Fast Global Synchronous ControlsuEvent-based controls (MRF)
u114.24MHz event rate, 50Hz fiducials
Dual layer control concept
uTiming precision < 10ps
OPI
Dual Layer Controls
EPICS
Channel Access

Event Generator

Central

IOC

IOC

IOC

IOC

EVG

EVR

EVR

EVR

MRF
Event Link

SH_A1
KL_B5/B6

SB_B

Injection

SB_Ae­ GunARC

e– BT (PF: 2.5GeV, 0.1nC)

Cont-ABC
KL_51/52
SB_C

SB_1

SB_2

SB_3

SB_4

SB_5

e+ BT (KEKB: 3.5GeV, 2nC)

e+ Target
Cont-1

Cont-2

Cont-3Cont-4Cont-5

Event Receivers
Introduction to Injector LINAC

e– BT (KEKB: 8GeV, 2nC,
PFAR: 3.0GeV, 0.1nC)

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Dual-layer Controls

One Machine, Multiple Virtual Accelerators (VAs)u Control/Monitor are carried dependent on a VA
v Mostly independent between VAs

u Independent parameter set for each VA, one of the VAs is controlled ata timev VAs for Injections (HER (e-), LER (e+), PF, PF-AR) and Linac-only in SuperKEKB projectIntroduction to Injector LINAC

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Pulse-to-pulse modulationu Four PPM virtual accelerators
for SuperKEKB andphoton science projects
u Multiple closed loops
overlappedu Since May.2019
Based onDual-tier controls withEPICS and event-system
Independent parameter setsfor each VA (every 20ms)
additional PPM VAs
for stealth beam measurementsin the future
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Simultaneous 4 + 1 Ring Top-up Injection
u Realized for the first time
³ SuperKEKB HER 7 GeV e–³ SuperKEKB DR and LER 4 GeV e+³ Photon Factory 2.5 GeV e–³ PF-AR 5.0 / 6.5 GeV e–v4 beams are modulated at 20
ms PPM
vMore than 200 pulsed devices
were constructed forSuperKEKB, as well as beam
and RF monitors
vInjection noise (background)
were well studied from the
2nd week of May
Introduction to Injector LINAC

HER

337.5 ± 1.6 mA (0.48%)

LER

348.2 ± 1.2 mA (0.34%)

PF

449.9 ± 0.1 mA (0.02%)

PF-AR

55.1 ± 0.2 mA (0.38%)

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Simultaneous Top-up Injections
uIntegrated luminosity improvement (example)
17.54 /pb in 5.15 hr(5 fills)
on May.6

41.64 /pb in 5.15 hr(top-up)on May.16

237%
improvement
Heavy work in April
was rewarded
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Upgrade plan

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Injector Linac Upgrade Items 2022 - 2026

B

A

C

1

2

3

4

5

Pulsed magnets/kickers High precision movers PCB capacitor renewal New energy compressor

RF gunIntroduction to Injector LINAC

Positron capture section Accelerating structure
K.Furukawa, Jan.2024

Challenges in Linac upgradeu Achieving the both of higher injection beam charge and lower
transverse/longitudinal emittanceu Maintaining higher availability and stability
u Establishing injection energy for higher resonances
u Solutions with upgraded hardware
v Precise pulsed magnets and fast kickers
v Energy compression system (ECS)v Accelerating structures to replace aged onesv Stable and high charge RF gun
v Replacement of a lot of capacitors with PCB in power modulators
v Movable girders for quads and structures in caseu With some Phronesis we can enjoy accelerators
v Phronesis [Greek]: Practical wisdom, Ability to understand the Universal
Truth
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Carbon Neutral Activities at Injector LINACHigh Performance Simultaneous Top-up Injections

69% Power Recovery from Pulsed Magnet Coils

High Power Conversion Efficiency at Magnet Power Supplies

High Efficiency RF Power Distribution

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Summaryu Injector LINAC continues multiple discipline injections
in simultaneous top-up injection mode (PPM).
u Emittance blow-up at the 2nd half of beam transport line
is still under investigation.
u The injector upgrade is implemented in 7 categories forthe final beam parameters with higher bunch charges
and lower transverse and longitudinal emittances.
Further upgrade is also investigated.

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Thank you

Papers and documents at <http://www-linac.kek.jp/linac-paper/general/>Introduction to Injector LINAC

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BackupIntroduction to Injector LINAC

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Further Injector Improvement Possibilitiesu After injector upgrade in 7 categories
v Difficult to foresee now which parameters to improve furtheru Under considerationv Further increase in positron bunch charge³ LER stored current is higher and beam lifetime is shorter³ Several possible plans exist

v Beam transport line thru the direct tunnel³ May relax CSR, etc³ May interfere with PF-AR operation, may require huge radiation shieldv Even higher energy³ Not difficult in ring hardware up to 12 GeV with different energy ratio³ Collision optics design should be investigated³ However, quite expensive modification at LINAC and beam transport linev Polarization³ Physics demand³ R&D for resources, space, meaningful bunch chargev…
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64Improved Precision/Flexibility Injections
HER: 800mA, 12.5 – 25 Hz,
1.4 nC, 1 bunch
LER: 1000mA, 12.5 – 25 Hz,
3.0 nC, 1-2 bunch
PF ring: 450mA, <1 Hz,
0.25 nC
PF-AR: 50mA, <1 Hz,
0.3 nC
vred: Ring current (mA)vblue: Bunch charge (nC)vgreen: Injection rate
(mA/s)

Typical 1-day Injections

Event-based
Control System
Every
20 ms

Injector operation hours and failure rates
8
Operation hours (hour)
Limited injection (%)
Beam stop rate (%)

Hours

7,000

F.B
7

6,000

6

5,000

5

4,000

4

3,000

3

2,000

2

1,000

1

(Achieved 200 thousand hours ofoperation at the middle of 2020)
0e− GunARC

Rates (%)

8,000

0
1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

PF Injection

The injector provide high availability with advanced high-current
and low-emittance injections for SuperKEKB as well as lightsource rings

Introduction to Injector LINAC

e– (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

Fiscal year

uF.B

e– (7GeV, 4nC)
e− GunARC

F.B

Four virtual
injectors haveenabled highefficiency
simultaneous
top-upinjections

PF-AR Injection

F.B
e– (6.5GeV, 0.2nC)

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65

Recent LINAC Development and Progress
Positron production yield reaching designed valueu Copper-Nickel alloy was applied to flux-concentrator andresolved the discharge issues
u Optimized with newly installed correctors and monitors
u 3 nC/bunch enough for present SuperKEKB operation

Present operation

Positron yieldu Planning to replace damaged 40 year-old 7% in
230 accelerating structuresu Succeeded to achieve high acceleration field
and low discharge rate with the first 4
structures
bridge coils
solenoid
top view
u Will install 12 more structures in 2023
DC quadLAS Accel. u Can reach Υ (6S)
10 nC
spoilerprimary e-targetstructuree+beam
injection ehole
Flux
Concentrator

Operation up to the last year

New accelerating structures were
designed and are being fabricatedDesign to achieve high performance

H. Egopulsed corr.
pulsed quad

Y. Enomoto
Flux concentrator

Steady progress of
positron beam

4 new structures installed

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