1. Status of the ERL Project in Japan
Norio Nakamura
for the ERL Collaboration Team
Institute for Solid State Physics(ISSP), University of Tokyo
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

2. ERL collaboration team
High Energy Accelerator Research Organization (KEK)
M. Akemoto, T. Aoto, D. Arakawa, S. Asaoka, A. Enomoto, S. Fukuda, K. Furukawa, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, T. Honma, T. Honma, K. Hosoyama, M. Isawa, E. Kako, T. Kasuga, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, T. Matsumoto, H. Matsushita, S. Michizono, T. Mitsuhashi, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, E. Nakamura, K. Nakanishi, K. Nakao, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, S. Ohsawa, T. Ozaki, C. Pak, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, K. Satoh, M. Satoh, T. Shidara, M. Shimada, T. Shioya, T. Shishido, T. Suwada, T. Takahashi, R. Takai, T. Takenaka, Y. Tanimoto, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, Y. Yamamoto, S. Yamamoto, Y. Yano, M. Yoshida
Japan Atomic Energy Agency (JAEA)
R. Hajima, R. Nagai, N. Nishimori, M. Sawamura
Institute for Solid State Physics (ISSP), University of Tokyo N. Nakamura, I Itoh, H. Kudoh, T. Shibuya, K. Shinoe, H. Takaki
UVSOR, Institute for Molecular Science
M. Katoh, M. Adachi
Hiroshima University
M. Kuriki, H. Iijima, S. Matsuba
Nagoya University
Y. Takeda, T. Nakanishi, M. Kuwahara, T. Ujihara, M. Okumi
National Institute of Advanced Industrial Science and Technology (AIST)
D. Yoshitomi, K. Torizuka
JASRI/SPring-8
H. Hanaki
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

3. Overview of the ERL project R&D status - Gun and SC cavities
Outline
Overview of the ERL project
R&D status - Gun and SC cavities
Compact ERL - Design study and building
Summary
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

4. ~ 100 fs (bunch compression)
ERL Project
Parameters of the 5-GeV ERL
KEK site
Parameter
Beam energy
5 GeV
Average current mA
Normalized emittance
mm·mrad
Energy spread (rms)
( ) 10-4
Bunch length (rms)
1 - 3 ps　(usual mode)
~ 100 fs (bunch compression)
RF frequency
1.3 GHz
5GeV ERL
Compact ERL
(cERL)
Parameters of the light sources
Parameter
Spectral range
30 eV - 30 keV
Average brilliance from insertion devices
ph/s/mm2/mrad2/0.1%bw
Average flux
> 1016 phs/s/0.1%bw
Number of ID’s
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

5. Compatibility of ERL and XFEL-O
(a) 5-GeV ERL
2-loop ERL
XFEL-O
(b) 7.5-GeV XFEL-O
Orbit Bump
Section
SC cavities
Possible scheme for compatibility of 2-loop ERL and XFEL-O
2-loop ERL
XFEL-O
Bunch train and pulsed bump for hybrid operation
SC cavities shared by introducing an orbit bump of a half RF wavelength
5-GeV ERL beam 2 times accelerated with the orbit bump off
7.5-GeV XFEL-O beam 3 times accelerated with the orbit bump on
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

6. 500-kV DC Photocathode Gun
500-kV gun with a segmented insulator
guard ring against field emission
HV terminal
field emission
support rod
guard ring
ceramic
gun chamber
cathode
anode
e-beam
Segmented insulator with guard rings employed
to mitigate field emission.
segmented insulator
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

7. HV Testing of 500-kV DC Gun Field distribution of the 500-kV gun
500 kV for 8 hours without any discharge
1200
HV terminal
1000
segmented insulator
current through resistors
800
height (mm)
600
radiation level is within the background.
no clear evidence for dark current.
400
6.8 MV/m on
guard rings
8.3 MV/m on
support rod
200
gun chamber
14.3 MV/m on
nose of support rod
(HV testing done without
a cathode electrode)
-200
200
400
600
R. Nagai et al., to be published in Rev. Sci. Instr.
radius (mm)
Talk by N. Nishimori for more details.
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

8. Test Injector Beamline
Test injector beamline set up in the PF-AR-south building.
Purposes :
To gain operation experience of the low energy beam.
To evaluate performance of the guns by measuring the emittance and bunch length with a diagnostic line.
To develop the 2nd 500-kV gun and the injector line used at cERL.
Laser system
1st solenoid
2nd solenoid
3rd solenoid
4th solenoid
1st view screen
2nd view screen
1st slit
(vertical)
(horizontal)
2nd slit
The same layout
as cERL injector
Beam diagnostic line (emittance &
bunch length measurements)
Beam dump line
3rd view screen
4th view screen
5th view screen
deflector
Beam Dump
200 kV gun
2nd 500 kV gun
test area
Test beamline
buncher
Laser room
Bending magnet
200kV Gun
2nd 500kV Gun
test area
Talk by T. Miyajima for more details.
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

9. Drive Laser System Laser system for gun commissioning at KEK
1.3 GHz, 515 nm, 20 ps, 1.5 W (10mA operation)
Yb fiber laser oscillator (Cornell type) + fiber amplifier
Second harmonic generation (SHG): 100mW output achieved
Construction of pulse shaping system and transport to the gun
Ti:sapphire psec laser for high-charge and short bunch tests
1.3 GHz, 800nm(tunable), 20 ps, 15 W (100mA operation)
Yb fiber laser oscillators (EO modulation & linear cavity types)
10W + 200W fiber amplifiers
SHG and OPA for tunable wavelength around 800 nm
Development of system components by AIST and ISSP
Yb fiber laser system
at KEK
oscillator
10W amplifier
Yb fiber oscillator and amplifier developed by AIST and ISSP
Ti:sapphire laser system at KEK
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

10. Injector SC Cavities (1)
・ Three 2-cell cavities for 5 – 10 MeV acceleration of 100 mA beam
・ Accelerating field : 15 MV/m
・ Two input couplers for each cavity
・ Four or five HOM couplers (loop and antenna types) for each cavity
Two input ports
HOM couplers
Basic cavity Parameters for Injector
Prototype 2-cell cavity
K. Watanabe, S. Noguchi, E. Kako et al., Proc. of SRF09, Berlin, 2009.
　Design of HOM couplers
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

11. Injector SC Cavities (2)
without pick-up probes of HOM couplers
30MV/m
44 MV/m
Heat-up of HOM probe
1st vertical test (2009 Apr.)
2nd vertical test (2010 Feb.)
Set-up for
a vertical test
Vertical test results of 1st prototype cavity
Maximum accelerating field : 30 MV/m
( 44 MV/m without HOM probes)
Heating of HOM probes for high fields
Stable operation for 11 hours at MV/m
11-hour
Lack of Liq. He
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

12. Injector SC Cavities (3)
SC Cavity
300-kW klystron
Two Input couplers tested in early 2010
300-kW klystron successfully developed
(S. Fukuda et al., 6th Conf. of Particle Acc. Society of Japan, 2009)
2nd prototype cavity with 5 HOM couplers fabricated.
Three real cavities under fabrication
Design of cryomodule almost completed
2nd prototype cavity
with 5 HOM couplers
Input coupler
Cryomodule
Water Cooling
Target
200 kW CW
Warm
Window
300 K
80 K
5 K
Zo =
41.5 W
Two input couplers for High Power Test
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

13. Parameters of main SC cavity
Main SC Cavities (1)
Target and feature of main SC cavity
Acceleraitng field: 15 MV/m (f=1.3GHz)
Beam current : 100 (acc.) (dec.) = 200 mA
HOM damping design
Large-aperture iris and beam pipe and HOM absorber
Eccentric-fluted beam pipe
(converter from quadrupole to dipole mode)
Parameters of main SC cavity
Frequency
1.3 GHz
Iris diameter
80 mm
Beam pipe diameter
100/120 mm
Rsh/Q
897 Ω
Ep/Eacc
3.0
HOM absorber
Eccentric-fluted beam pipe
HOM absorber
9-cell cavity design
E-single
C-single
C-single
E-single
Two type of single-cell cavities
Vertical test
 Eacc > 20 MV/m achieved for both cavities
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

14. Main SC Cavities (2) 2K 4.2K Maximum accelerating field：15-17 MV/m
8-9 iris
(150 °)
X-ray mapping by a rotating mapping system
1cell
2cell
3cell
4cell
5cell
6cell
7cell
8cell
9cell
Broad X-ray
signal
Angle[deg]
180
360
9-cell cavity 2K
4.2K 15 10 5 20 25 30
Eacc [MV/m]
1011
1010
109
108 Q0
Vertical test
Array of
PIN diodes
Maximum accelerating field：15-17 MV/m
Accelerating field limited by field emission
A tip found on an iris between 8th and 9th cells
 Vertical test resumed after polishing the tip
Sharp X-ray signal
Tip on an iris of the cavity
(f : several hudred mm)
K. Umemori, T. Furuya et al., SRF09.
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

15. Main SC Cavities (3) Cryomodule
Ceramic windows and bellows of an input coupler fabricated and tested  Ceramic window design slightly modified.
HOM damper prototype with a comb-type RF shield fabricated and HOM absorbers tested.
Cryomodule design containing two cavities with three HOM dampers in progress.
HOM dampers
Cavities
Input couplers
Input coupler
HOM damper
Cold window
Prototype
HOM damper
without absorber
Left: outside
Right: inside
Bellows
Warm window
Cooling
air
Cold window
Warm window
RF power
H. Sakai et al., SRF09.
M. Sawamura et al., SRF09.
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

16. Compact ERL Compact ERL East Counter Hall
Before constructing a large-scale ERL facility, we need to demonstrate the expected ERL performance using key components.
Compact ERL
Parameters of the Compact ERL
Parameters
Beam energy
MeV
Injection energy
MeV
Average current mA
Acc. gradient (main linac)
15 MV/m
Normalized emittance
mm·mrad
Bunch length
(rms)
1 - 3 ps (usual)
~ 100 fs (with B.C.)
RF frequency
1.3 GHz
East Counter Hall
Conceptual Design Report published in 2007
KEK Report /JAEA-Research
R. Hajima, N. Nakamura, S. Sakanaka,
Y. Kobayashi eds.
100 m

17. Injector design for cERL
Injector components of cERL
Photocathode DC gun
Two solenoids
Bunching cavity (Buncher)
Three SC cavities
Five quadrupole magnets
Merger (using three bending magnets)
Initial Conditions
Electron distribution on cathode: beer-can shape
Initial charge: 80 pC
Parameters optimization
Generic algorithm
Tracking code GPT
Space charge effects included
No CSR in merger
Optimization result
Rectangular type gives smaller emittance than the sector type.
Normalized emittance 0.4 – 0.5 mm mrad for 2 – 3 ps bunch length.
(1) Sector type (bending angles：-19, 22, -19 degree)
Normalized rms emittance
0.4 ～ 0.5 mm mrad
(2) Rectangular type (bending angles：-16, 16, -16 degree)
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

18. Error Analysis of cERL Injector
Amplitude error in RF cavity
Phase error in RF cavity
Summary of error analysis results
An example of error analysis results
(Arrival time offset vs RF amplitude error)
Gun ripple < 0.1 %, RF amplitude error < 0.1 %, RF phase error < 0.1 °
Talk by T. Miyajima for more details.
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

19. Optics Design of 1-loop cERL Compact ERL(1-loop model)
Chicane
Long straight section
1st TBA arc
2nd TBA arc
Beams
Extractor
Merger
Beam dump
Main SC cavities
Injector
Gun
Compact ERL(1-loop model)
Basic parameters
Beam energy
125 MeV
Beam current
10 – 100 mA
Normalized emittance en = e/(gb)
1 mm·mrad (77 pC/bunch)
0.1 mm·mrad (7.7 pC/bunch)
Energy spread (rms)
< 3 10-4
Bunch length (rms)
1 – 3 ps (normal recirculation)
~ 100 fs (bunch compression)
High current mode: 100 mA, 1 mm mrad
Low emittance mode: 10 mA, 0.1 mm mrad
Emittance almost preserved
CSR effects included
Optics functions
(in high-current and low-emittance modes)
T. Shiraga, N. Nakamura et al., PAC09
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

20. Bunch Compression in cERL
st =56 fs
(3)
(4)
Main SC Cavities
Dump
Merger
injector
1st arc
(R56>0)
2nd arc
(R56<0)
Chicane
Extractor
Long straight section
Beams
(2)
(6)
only b, x,y opt.
(1)
Initial condition:
st =1 ps
Q=77 pC
en=1 mm mrad
time
x-position
y-position
Momentum
5 cm
6 mec
12 ps
(5)
Gun
sx,y opt.
Bunch compression and decompression successfully simulated.
Optics also optimized for avoiding serious beam loss after decceleration.
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

21. Error Effects of Main SC Cavities
DV/V -0.5%  +0.5%
1st arc
2nd arc
Orbit distortion and emittance growth due to +1-mm horizontal alignment error of 8 main SC cavities in low-emittance mode and their correction
DY=0mm
st=56 fs
DY=±1mm
st=267 fs
DfRF +1.0°  -1.0°
Bunch profile at exit of the 1st arc with ±1-mm vertical alignment error of 8 main SC cavities in bunch compression
Bunch length and arrival time variations
at exit of the 1st arc due to RF amplitude and phase errors in bunch compression
Bunch length and arrival time variations due to RF amplitude and phase errors
 0.01 % amplitude and 0.01 deg phase control required for bunch compression
Orbit distortion, emittance growth and bunch lengthening due to alignment error of SC cavities
 Orbit correction using eigenvector method with constraints(EVC) successfully applied
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

22. Optics Design of 2-loop cERL
Merger
Branch
chicane
Adjustment chicane
Extractor
Beam dump
Main superconductor cavities
DC gun
Layout of 2-loop cERL (tentative)
Optics of 2-loop cERL (tentative)
M. Shimada et al., ERL09.
Optics design of 2-loop cERL in progress
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

23. Reconstruction of the East Counter Hall for the compact ERL
cERL Building
Feb. 2009
Jan. 2010
The hall is being cleaned.
Liq. He refrigerator is being installed.
East Counter Hall
Reconstruction of the East Counter Hall for the compact ERL
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

24. Final version of the compact ERL(2-loop, 100mA, 245 MeV)
Plan View of the Compact ERL (1)
SCC vertical
test area
Magnet
power supplies
RF sources
Liq. He refrigerator system
Laser hut
Compact ERL
Electronics hut
SCC R&D area
Vacuum hut
Final version of the compact ERL(2-loop, 100mA, 245 MeV)
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

25. Plan View of the Compact ERL (2)
Liq. He refrigerator system
RF sources
Laser hut
SCC R&D area
Magnet
power supplies
SCC vertical
test area
Compact ERL
Electronics hut
Vacuum hut
Commissioning will start with a minimum version (1-loop, 10mA, 35 MeV) in FY2012.
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

26. Summary ERL Project R&D in progress Compact ERL (cERL)
Compact ERL (final version : 2 loop, 245 MeV, 100 mA)
Two-loop 5-GeV ERL and 7.5-GeV XFEL-O
R&D in progress
500-kV DC photocathode gun and injector beamline
Drive laser system for the gun
SC cavities for both injector and main linacs
Compact ERL (cERL)
Design and error analysis of injector and 1-loop cERL studied
Optics of a 2-loop cERL under design
East Counter Hall at KEK renewed as cERL building
Commissioning (35MeV, 10mA, 1 loop) planned in FY2012
Here is a quick summary.
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory

27. Thank you for your attention!
Norio Nakamura, FLS2010, March 1-5, 2010, SLAC National Accelerator Laboratory