JAERI-Conf 95-021

PA02
NIJI-111 Superconducting Compact Light Source Facility
Katsuji Emura, Tsuyoshi Haga, Tsuyoshi Shinzato, and Hiroshi Takada
Harima Research Laboratories, Sumitomo Electric Industries, LTD.
1431-12, Harima Science Garden City, Kamigori, Hyogo, 678-12 Japan
ABS1RACf
Sumitomo Electric Industries established a synchrotron
radiation (SR) facility named "Harima ResearchLaboratories" in 1993. The facility is located in Harima
Science Garden City where the large SR facility "Spring-8"
is being under construction. Main purpose of ourlaboratory is to develop the advanced technologies on SR
application, particularly for micro-fabrication, photochemistry and x-ray tomograph. In the facility, a 600MeV
superconducting compact SR ring "NIH-III", a toOMeY
compact linac and five beamlines have been installed.
Nowadays, NIJI-III usually provides SR light to users for
16 hours in a day.

1. Introduction
Recently, it has been discovered that SR has potentialfor the industrial applications, thus a compact, easy-to-use
SR machine has been awaited in this area. We havecontinued our R&D efforts to develop compact SRmachine. It mainly consists of a linac and an SR ring.
Both of them require compact design. We first launched thedevelopment of a compact SR ring under the direction of
the Electrotechnical Laboratory of the Agency of Industrial
Science and Technology. Incorporating many advanced
technologies, such as a superconducting bending magnet,
the compact SR ring named "NUl-III" was completed 1·2,3).
NIH-III was achieved its design goal of 200mA stored
current at 600Me V and the demonstration of large area
exposure, 50mm X 50mm, using the electron-beam
wobbling method4 >. Based on these results, at the end ofJuly 1993, NIH-III was transferred from Tsukuba to our
newly opened Harima Research Laboratories in order toaccelerate the development of advanced SR application
technologies.
For the linac, we had accumulated the basic engineering
technologies needed for system design through joint
research with ISIR Osaka University, and completed thedevelopment of a compact linac by ourselves in 1993. The
linac has an accelerating gradient of 22Me V/m, which is
the world's highest class for commercial machines 5·6>. We
have thus succeeded in downsizing the linac, as well as theSR ring.
2. Facility overview?>
Figure 1 is a bird's eye view of our facility. Both thelinac and SR ring are installed in an accelerator room
which is surrounded with lAm-thick shielding wall. Of the3,500 square meter total floor space, 1,500 square meters
is occupied by an accelerator room and an experimental
hall.
The linac's output beam, typically macropulse currentof lOOmA at lOOMeV, is introduced into the SR ring
through the beam transport system approximately 25m
long. It injects an electron beam with small beam radius,
less than 5mm, and minimum achromatism into the SRring.

FIG. 1. Bird's eye view of the first floor ofHarima Research Laboratories.
3, SR ring "NIJI-III"
A schematic configuration and main parameters ofNUl-III are summarized in Fig.2 and Table I, respectively.
NIH-III is a rectangular-shaped ring with approximate
dimensions of 3.5 X 6.4m. Since its lattice structure is
likely Chasmann-Green lattice, a dispersion-free condition
can be obtained in the Jong straight section and dispersion
functions are kept small in the bending section. The lattercharacteristic is the key issue for realizing a small beam
size at the light source point. Both horizontal and verticalbeam sizes are smaller than 0.5mm in the bending section.
The superconducting bending magnets can generate amaximum magnetic field of 4.0T, which enables us toobtain a peak wavelength of sA at beam energy of
600MeV as shown in Fig.3. The most notable feature ofNIJI-III is the power leads of the superconducting bendingmagnets. These are made of high temperature (HTc)practical superconductors fabricated by ourselves. Thesepower leads offers advantages of reductions in Joule loss,
suppression of ambient heat transfer and hence improving
the economy of the cryogenics.
At the injection energy of lOOMeV, a maximum stored-26-JAERI-Conf 95-021

current of above 150mA was achieved with anaccumulation rate of 30mA/s. No transverse instability isobserved at the injection energy. Although sextupole andoctapole magnets are installed in NIJI-III, those are noneed to excite for electron storage.
Accelerating the stored beam to the final energy of600MeV is accomplished by ramping all magnets
simultaneously. Beam acceleration has been carried out inwhich currents of more than 100mA can be accumulated at
the final energy. A ramping ratio between the exciting
currents of superconducting bending magnets and of
normalconducting quadrupole magnets is not a constantvalue through the acceleration, from 100MeV to 600MeV.
This is attributed to magnetic saturation on the quadrupolemagnets at high energy region and eddy current generated
in the vacuum ducts in the bending section.
The beam lifetime was approximately 6 hours for thestored current of lOOmA at 600MeV. The lifetime isthought to be limited by the vacuum pressure of
2 X 1o- 9Torr. It will be lengthened by a decrease in pressure
rise. NIJI-III usually operates day and nigh~ when NIJI-III
provides SR light to users. Electrons are usually refilled
into NIJI-III 4 times per day.

N' 60

600MeV, 200mA'0ro....

.....E 40.....

....Q) -<!
~~.s 20
a:
00.

(f)

0102

101

100

wavelength (A)FIG. 3. Output SR spectrum
4. Electron injector
Electrons for injection into NIJI-III are provided by acompact linac. Main parameters of the linac is listed inTable II. The linac normally produces electrons at lOOMeVwith a pulse width of 1 f.l. s. Our final goal of developmentof the linac is to realize a compact machine, as well as theSR ring. At the end of 1993, an accelerating gradient of
22MeV/m was achieved, which is the world's highest classfor commercial machines. Also, the linac has anothernotable feature. It can produce a long-pulse beam of 10 f.l. s
which is suitable for free electron laser (FEL)
oscillation8, 9l. Our activities on FELs are summarized inlatter section.
TABLE II. Main parameters of the linac .
cathoderf frequency
beam energy
macropulse current
energy spreadnormalized emittance
repetition rate
accelerating gradient
Klystron

E"'"'

FIG. 2. Schematic configuration of NIJI-III
TABLE I. Main parameters of NIJI-III
Electron energy
Stored beam current
Circumference
Bending magnetic fieldrf frequency
Harmonic number
Critical wavelength
Horiwntal betatron tune
Vertical betalron tune
Momentum compaction factor
Emittance

600MeV

200mA
18.89 m
4.0 T
158.7 MHz
lO

l3A
2.37
1.35
0.087

0.38 mmmrad

EIMACY646B
2856 MHz
100 MeV (short pulse)
76 MeV (long pulse)IOOmA
0.5%

60x mmmrad
2 pps
22 MeV/m

TH2146

Electron gun is a thermionic triode gun based on adispenser cathode assembly (EIMAC model Y646B). Ahigh d.c. voltage of 200kV is applied to anode-cathodegap in order to obtain high beam brightness. A brightnessof more than 10 10A/m 2 rad2 has been achieved inexperiments carried out before installation into the linacsystem.
The bunching system consists of three tubes:
subharmonic prebuncher (SHPB), prebuncher (PB), andbuncher (B). The phase bunching characteristic of thissystem is evaluated by a ballistic-model simulation. As aresult, for the electrons emitted from the gun, more than
40% are bunched into a 50 degree phase spread at theentrance of the bunchcr. The SHPB is a standing-wave
cavity with a resonance frequency of 476MHz. It was madeof stainless-steel. A portion of the inner surface of thecavity was coated by OFHC in order to optimize both ashunt impedance and Q-value of the cavity.

-27-

JAERI~ConfThe accelerating tube is a disk-loaded waveguide witha constant gradient structure. There are no rf windows or
bellows in the waveguide system between the acceleratingtubes and the klystrons, in order to withstand the rf power
even if the klystron generates its maximum rf power of
45MW. To stabilize the energy of the output electrons, twoapproaches are principally effective. Output power of theklystron is designed for stable, since its modulator
generates a voltage pulse stabilized within 0.3% owing toparallel pulse forming network (PFN). Also, the resonancefrequency of the accelerating tube is stable, since its
temperature is controlled within ± 0.02 degree by a watercooling system.
5. Beamlincs and SR applications
WC have installed five l;>eamlincs in NIH-III. Outlineof the bcamlincs are summarized in Table III. In part ofthem, the distance from the SR light source point to theirradiation chamber is less than 3m, which enables us toobtain high photon density by no means inferior to Ge Vclass medium scale SR ring.
In this section, we briefly describe our representative
activity on SR applications. Recently, micro-fabrications
using a deep-etch x-ray lithography are demanded inseveral fields such as a precision engineering, advanced
communication technology, medical engineering and soon. We have studied on LIGA process, German acronym for
Lithographic, Galvanoformung, Abformung, which allows
microstructures of any lateral shape to be fabricated withstructual heights of several hundred micrometers. We havesucceeded in the development of PZT microstructures for
micro-ultrasonic transducers lll).
TABLE III. Beamlines
BL-1

BL-11

BL-IIIa

BL-IIIb

BL-IV

Photon0.02-0.13
energy (keVJ

1-10

3-IO

0. I-1.5

0.1-10Mirrortoroidal

none

none

Monochro~toroidal
grating
photochemistry

mator

Experiments

none

micro-double
crystaltomograph
XAFS

cylindricaltoroidalspherical
grating
photo-none

nonephoto excitedemission
fabrication--------=---------------.:.---'--pro~ess

95-021carried out for lattice design. The BTS consists of two
bending magnets and five quadrupole magnets. The
bending angle of the two bending magnets is very small,25.0 degree without edge-focusing, to realize the quasiisochronism.
TABLE N. Experimental conditions of FEL
beam energy
peak current
K parameter
magnetic field
FEL wavelengthgain

50 MeV
25A
0.84
0.23 T
2.8 JJ m
10%

Our undulator is the Halbach type using Nd-Fc-B
permanent magnets. Total length of the undulator is 2m
with periods number of 50. A roundtrip time in the opticalresonator is set to be 24th harmonics of the micropulseinterval t~me of' 2.1ns. The optical resonator consists of
two concaved Au-coated OFHC mirrors.
Gain calculation were carried out in accordance withthe reference No.ll. Small signal gain on ourexperimental system are estimated to be 10%. In thiscalculation, five modified coefficients are necessary tocalculate. In our condition, the modified coefficient causedin the energy spread of the electron beam is by far smallest
in them. Therefore, we have tried to find out the optimum
conditions which enable to obtain the energy spread ofless than 0.9%.
7. Conclusion
NIJI-III superconducting compact light source facility
was operated at our newly opened Harima ResearchLaboratories in Harima Science Garden City. Nowadays,
NIJI-III routinely operates in 600MeV-100mA andprovides SR light to users for 16 hours in a day. We are justaccelerating the development of advanced technologies onSR applications. Also, we intend to upgrade quantum
radiation equipment such as FEL.
RefeNn~-.:sI, H.Takada et al., Jpn. J. Appl. Phys. 30, 8 (1991)

6. Free electron laser <FELl
Recently, we proceeded with studies on FEL in an
infra-red region using our compact linac. Experimental
conditions at present are summarized in Table IV. We havesucceeded in observing a spon.taneous emission ranging
from 2 to 10 JJ m. Main components of the FEL system arebriefly described in following section.
The linac's output beam is introduced into an undulator
section through the beam transport system (BTS). The BTS
for FEL requires very severe spec: double achromatic andquasi-isochronous should be realized in the undulator
section. Simulations concerning the beam optics were2, K.Emura et al., Proc. 7th Symp, Accelerator Science andTechnology, RCNP Osaka, 344 (1989)
3, K.Emura et al., Rev. Sci. Instrum. 63, 1 (1992)
4, T.Tomimasu, Jpn. J. Appl. Phys. 26, 741 (1987)

5, K. Emura et al., Sumitomo Tech. Rev. 39 (1995)
6, T.Haga et al., in this proceedings
7, H.Takada et al., "Synchrotron Radiation Facilities inAsia", IONICS, Tokyo (1994)
8, K.Emura et al., Proc 20th Linear Accelerator Meeting inJapan, Osaka (1995)
9, T.Shinzato et al., in this proceedings
10, Y.Hirata et al., Proc. IEEE Mien> Electn> Mechanical
Systems Workshops ( 1995)
11, P.W.van Amersfoort et al., The FELIX pr<>ject status report April 1988,
Rijnhui1.cn Report ((-176-28-