MAINTENANCE AND IMPROVEMENT OF THE SYNCHROTRONRADIATION SOURCE HiSOR
Presented by Kiminori GOTO
Hiroshima Synchrotron Radiation Center, Hiroshima University
2-313 Kagamiyama, Higashi-Hiroshima 739-8526, JapanHiSOR is a synchrotron light source constructed at
Hiroshima Synchrotron Radiation Center, Hiroshima
University in FY1996. After some improvement, upgradeand tuning, the storage current of the HiSOR was up to200mA in May 2000. As the stored current increased
more and vacuum degree was better by repeating
degassing operation, the beam instability problem atinjection and at acceleration was severer. At present,changing the operation point at injection and updating thetracking pattern at acceleration from 150MeV to 700MeV
is only a way to suppress the beam instability of theHiSOR. In near future, we will get approval from theradiation protection authority for the operation with350mA. Then we are getting ready for upgrade of theHiSOR in order to operate stably.

1 INTRODUCTION
A compact synchrotron light source with a nickname"HiSOR" was constructed by Sumitomo Heavy Industries
Ltd.(SHI) for the research and education at Hiroshima
Synchrotron Radiation Center(HSRC), Hiroshima
University[1,2]. The injector is a 150-MeV microtron[3].
The injected electrons are stored at 150-MeV, andaccelerated to 700-MeV and stored. After the injection ofelectrons to the storage ring, the microtron is used as aninjector for another electron circulator ring REFER(Relativistic Electron Facility for Education andResearch) to investigate the interaction of the relativistic
electron with matter (crystal). It is a property of theVenture Business Laboratory of Hiroshima University.
The total number of the HSRC permanent staff is 8.
Five of them are operators(almost of them are beamline
staffs and users) and one is a maintenance and machine
staff. The maintenance of the light source system and thetuning with beam by the machine staff are scheduled on
every Monday, and the light source is opened to users
from Tuesday through Friday. The operation schedule forusers is designed for the electron injection, generally
taking for several minutes, into the storage ring at 9:30 in
the morning once a day. The acceleration of the 150 MeV
electrons up to 700 MeV is completed within two minutes.
The 150 MeV electron beam from the injector microtron
is then switched towards the REFER. The operation ofboth the REFER and the storage ring ends at 18:00. The
job of operators is to turn on devices, to accelerate to700MeV after injection and to switch towards the REFER
in the morning and to turn off devices in the evening.
Every operator is bound three times a month while about

two hours by the job. Since storage current up to 200mA
in May 2000, it is hard without help of the machine staff
for operators to inject into the storage ring and accelerate
the beam also.

2 STORAGE RING
The storage ring is of a racetrack type. The bending
field is as strong as 2.7 tesla, so the total radiation power
and the critical wavelength are comparable with thosefrom 1-GeV ring with usual bending field, about 1.2 tesla.
At one straight section, a linear undulator is installed, andin another straight section, a linear-helical undulator isinstalled[4]. We can control the elipticity of thesynchrotron light by controlling the magnet array
configuration. The betatron function and dispersion
function of HiSOR storage ring is shown in Fig.1. The
pole gap of the bending magnet is as narrow as 42 mm toproduce strong magnetic field, then to suppress thevertical betatron function, an edge focusing scheme isemployed. The vertical betatron function at the straightsection should be also small because the undulator gap isas narrow as 24 mm. The betatron function of this part iscontrolled by quadrupole doublet at both ends of thestraight section.
1412Beta, Dispersion [m]Abstract

βx10βyη

8642005101520s [m]Figure 1: Beam optics of the HiSOR storage ring.

3 MAINTENANCE
Preventative maintenance by the maker is built intothe HiSOR operating schedule. In Table 1, Maintenance isthe number of the day for preventative maintenance and it
includes days for some planned improvements. InFY1998, 98 days were used for test and tuning. In thoseBending
MagnetElliptical
Undulator

RF Cavity
Q-Magnet
Steerer

Inflector

C.T.

LinearUndulator

Gate Valve

He-Refrigerator

Perturbater

VacuumChamber
SR Beam Line

Figure 2: HiSOR ring.

1.65
1.85

1.7

1.75

1.8

1.85
1.85

1.8

1.8

ν yused now
1.75

1.75
used before

Table 1: The number of the day for maintenance, repairand tuning.
1998199920002001

Maintenance

4044

1730Repair with failures

70536744

Test and tuning

9847

936

total

208

144

93110

1.7

1.7

1.65
1.65

stored current was less than 100mA. Then injection point
was changed to suppress the beam instability. Fig.3 shows
the injection point used now. Though it is seemed severer
than old point because the new point is close to the strong
resonance, the resonance suppresses the beam instability
and it is not easy but possible to inject until to 200mA at
this point until now.

1.7

1.75

1.8

1.65
1.85

νxFigure 3: Tune diagram.
days, Monday and Tuesday were scheduled for themaintenance, tuning and self-cleaning by the synchrotron
radiation. The stored current was made into 200mA mode
from 100mA mode in May 2000. The vacuum degree ofthe storage ring became better by the self-cleaning day by
day and this improved the beam lifetime but began tomake the injection and the acceleration sensitive. InFY2001, the beam instability was severer and it was too
hard to inject the beam up to 100mA. Beam failures inTable 2 show this. It means the number of the day when

Table 2: The number of the day for users and the day offailures by beam instabilities.
1998

1999

2000

2001

User days

61

99

139

150

Beam failures

001

12

4 IMPROVEMENTThe HiSOR facility was completed in 1997, five years
ago. Since then, we have made some improvements onthe light source. Some of them are as follows:
••
•
•
•
•
•

Upgrade of the storage ring vacuum system[5].
Install of the kicker magnet for the tune
measurement system and the single bunch
operation[6].
Install of four steering magnets to correct more theorbit distortion.
Install of steering magnets at the beam transport line.
Change from shunt resistors to DCCT used as thesensor of power sources.
Divide of the RF cooling water system from the main
cooling water system.
Upgrade of the Cryosorption pump system and its
cooling water system.

In near future, the stored current will be 350mA mode
from 200mA mode. And the time opened for users will beexpanded to 24 hours from about 10 hours. But it is
impossible to operate stably in the present machinecondition. Then we are getting ready for upgrade of themain cavity and install of the Landau cavity. The
operating system used now[3,7] has no capacity tooperate more devices then replace of the operating system

is prepared with help of operating system crews at Spring8.

5 REFERENCES[1] K. Yoshida et al., “Compact Synchrotron Light
Source of the HSRC”, J.Synchrotron Rad. 5 (1998)
345.
[2] K. Yoshida et al., “Commissioning of a Compact
Synchrotron Radiation Source at Hiroshima
University”, Proc. of APAC’98 (Tukuba, Japan, 1998)
p.653.
[3] T. Hori et al., “Improvement of 150 MeV Racetrack
Microtron”, Proc. of PAC’91 (1991) p.2877.
[4] A. Hiraya et al., “Undulators at HiSOR-Compact
Racetrack Type Ring”, J. Synchrotron Rad. 5 (1998)
445.
[5] K. Goto et al., “Two Years of the Synchrotron
Radiation Source HiSOR”, Proc. of The 12thSymposium on Accelerator Science and Technology(Saitama, Japan, 1999).
[6] F. Masaki et al., “Measurement of Beam Parameterson the Synchrotron Light Source HiSOR”, Proc. ofThe 12th Symposium on Accelerator Science andTechnology (Saitama, Japan, 1999).
[7] K. Aoki et al., “A PC-based Control System forHiSOR”, Proc. of ICALEPCS’97 (Beijin, China,1997).