The CeB6 Electron Gun for the Soft-X-ray FEL Project at SPring-8 May 25, 2004 DESY, Hamburg, Germany T. Shintake, H. Baba, T. Inagaki, T. Tanaka SPring-8 / RIKEN Harima Institute H. Matsumoto High Energy Accelerator Research Organization (KEK) K. Togawa SPring-8 / RIKEN Harima Institute
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The CeB6 Electron Gunfor the Soft-X-ray FEL Project at SPring-8
May 25, 2004DESY, Hamburg, Germany
T. Shintake, H. Baba, T. Inagaki, T. TanakaSPring-8 / RIKEN Harima Institute
H. MatsumotoHigh Energy Accelerator Research Organization (KEK)
K. TogawaSPring-8 / RIKEN Harima Institute
Where is SPring-8 ?
SCSS
SPring-8
SPring-8
Harima Science Garden City
KKEK
SPring-8 Compact SASE Source (SCSS Project)SCSS
Bunch
Compressor
476 MHz
Buncher
Energy
Filter
Electron
Gun(500 keV)
476 MHz
Booster
Cavity
(1 MeV)
L-band
Pre-Linac
(20 MeV)
C-band Main Linac (1 GeV)
In-Vacuum UndulatorHigh-Power
Short-Pulse
Soft X-ray
3.6 nm
The project to construct a soft X-ray free electron laserbased on SASE (self-amplified spontaneous emission)has started at SPring-8.
The gun must produce lower emittance beam !!
Beam Parameters at Undulator
Charge ~ 1 nC/bunch
, rmsnε 2 π mm.mrad <~
Requirements of X-FEL Electron SourceSCSS
1) Low Emittance
2) High Charge
3) High Beam Quality 4) Stable
SASE-FELSaturation
User Experiments
<1 π mm.mrad
~1 nC/bunch
Small Jitter, Long Lifetime
Precise AlignmentProtection of Undulator MagnetNo Beam Halo, No Dark Current
Thermionic Gun RF-Gun
1:20
Beam
Chopper
(puls
e s
hapin
g)
Energy Filter Sub-harmonic
Buncher
476MHz
Booster Cavity
L-Band
Buncher
L-Band
Accelerator
Energy
Analyzer
To
Main Linac
Ve
rtic
al S
lit
(beam
chopper)
Ho
rizo
nta
l S
lit
(energ
y g
ate
)
HV Pulse Gun
476 M
Hz, 200 k
V
Low Emittance Injector for SASE-FEL
Co
llim
ato
r
Cathode
CeB6 single-crystal
φ3 mm
1450 deg.C
εn 0.4 π µrad
Vp 500 kV
Ip 3 A
tFWHM 1.5 µsec
fr 60 pps
K 0.01 µA/V1.5
Filter 400~600 kV
Ip 3 A
tFWHM 0.3 nsec476 M
Hz, 700 k
V
1428 MHz
10 MV/m x 1 m
Traveling Wave
1428 MHz
10 MV/m x 2 m
Traveling Wave
Vp 20 MV
Ip 100 A
tFWHM 10 psec
Q 1 nC
2002 July
400 800 3000
HS, VS : Steering
EZ : Einzel Lens
Troid Current Monitor
Screen Monitor
Why do we use the HV thermionic gun ?SCSS
1) Stable and Long Lifetime ・Simple.
・High power pulsed technology and thermionic cathode technology is well established, and used for various electron devices.
2) Low Emittance and Uniform Emission ・Single crystal cathode has very flat surface.