Proposal for Japan-US collaboration onNew Test Facility for Novel Accelerator R&D

(FACET at KEK)

M. Yoshida, K. Nakajima,M. Sato, S. Matsumoto,

M. Nozaki, S. YamaguchiNovel Accelerator Promotion Office in KEK

Japan-US collaboration for me• Development of klystrons

and other electron tubes.(Mitsubishi / Toshiba)Technologies are based on Japan-US collaboration.

• Concerning to beam driven accelerator region,U.S. has many experiences for more than 10 years.We have to learn more about this region.

=> ILC after burner etc.

New concept IOT for ERL

DRFS klystron / L-band 40 MW etc.

FACET at SLAC

1.19 GeVσz= 5.5mm=18 psεx,y=50 x 5 mm ・ mrad

23 GeV, 3nCσz=14μm=50 fsσx,y = 10 μmβ ～ 1 m

0.4 ps

At FFTB experiment : Gradient : PWFA(>30GV/m), DWA(>16GV/m).Total acceleration voltage : > a few GeV.

We are discussing with Dr. Mark Hogan.

FACET at KEK

BCS

Install Photocathode RF-Gun

z=1 ps, q > 5nC, εx,y < 20 mm ・ mrad

Total length ~400m => 9 GeV

8 GeV LINAC from 1998

e+ Damping Ring(under construction)

e- 9 GeV, 5nCσx,y = 35μ ｍ (β ～ 1m)

e+ 4 GeV, 5nCfrom damping ring

ExperimentalArea

ps modulatedlaser 40 TW laser

Target for FACET in KEK• Continuous novel accelerator facility until Super-

KEKB shutdown ～ 2025 ?

• Short pulse laser complex facility : Laser modulated photo cathode RF-Gun and LWFA injector for femtosecond witness beam.

• User facility for University etc.～ 100 fs electron bunch

LWFA fs witness bunch

DWA (or PWFA)

Ex. DWA

2

,

42 / ( 0.1 )

81

b e ez dec t

z

N r m ceE GV m ps

a a

×Transformer Ratio(～ 3)

Single-wall DWA:

Multi-wall or photonic DWA with multi femtosecond bunch:

For microwave:Klystron : 350 kVAccelerator : 35 MV/m => transformer ratio = 100

+

Laser modulatedmicro bunch structure

Higher Transformer ratio

DWA experiment is just started using another low energy fs beam.

8 GeV LINAC Third Switch YardKEKB(continuous inj.)

PF (top up)

AR(2 inj./day)

8 GeV LINAC Gun

Third Switch Yard

Damping ring(under construction)

Experimental Area (beam damp)

Beam diagnostic station &FACET at KEK LINAC Beam damp

Pulse bend for PF

～ 2014 : no injection to KEKB↓

2014 ～ : beam switch for KEKB/PF & Beam Damp

Key technologies• Laser plasma injector

– The witness beam.– Sub-fs beam.

• Fast beam switch (completed)– Event system– Pulse bend

• RF-Gun (will be installed soon)– Velocity bunching DAW => high charge & low emittance– Modulated laser => micro bunch structure.

• X-band for harmonic compensation and bunch compression.– Also use for Beam Diagnostic Station for LINAC Upgrade : B

unch Length / Sliced Emittance

Laser Plasma Injector

• Stacked capillary

• 40 TW laser is enough for self-injection– Upgrade existing TW laser

Discharged byYAG laser

LWFA injector for femtosecond witness beam

Fast beam switch• 50 Hz Event System (completed)

• Pulse Bend (installed)

Damp

FACET

Beam Damp Mode

KEKB e-KEKB e+

ExperimentalArea

New beam line is required

Velocity bunching DAW RF-Gun

1/4 Transient Angle1z ps

Linear velocity bunching will be expected to generate higher charge bunch > 10nC

+ Laser modulation

Micro bunchstructure

X-band• Harmonic compensation (suppress second

term)

• Bunch compression

42

2

1cos 2 cos 2 1

,

S X SS X X

SXX X

S X

z zE z V V az V

N

VN V

N

3sin 2

/ 56

BC BCX

BC

zE z V bz cz V

z z E E R

Nextef : =>- 3 PPM klystrons.- 150 MW

Summary• FACET at KEK is considered to

construct the beam driven and short laser complex facility, it has some different aspects compared with FACET at SLAC.

• KEK 8 GeV LINAC has unique ability for novel accelerator test facility except for SLAC in the world.

• It is expected to become a good complementary project to FACET at SLAC.