• T. Semba, T. Yamamoto
  Hitachi Ltd., Ibaraki-ken
• M. Abe
  Hitachi, Ltd., Power & Industrial Systems R&D Laboratory, Ibaraki-ken
• Y. Iwasaki, T. Kaneyasu, S. Koda, Y. Takabayashi
  SAGA, Tosu

A 4T superconducting wiggler for 1.4GeV synchrotron radiation facility Saga Light Source (SAGA-LS) was developed and manufactured. The wiggler consists of one superconducting magnet as main-pole and two normal conducting magnets as side-poles. The superconducting coils are wound with NbTi wires on iron poles, which are directly cooled by a 2-stage GM cryocooler. The structure of the wiggler is made for compactness and cryogen-free operation. This paper describes its magnet design and manufacturing processes.

• N. Yamamoto, M. Hosaka, H. Morimoto, K. Takami, Y. Takashima
  Nagoya University, Nagoya
• Y. Hori
  KEK, Ibaraki
• M. Katoh
  UVSOR, Okazaki
• S. Koda
  SAGA, Tosu
• S. Sasaki
  JASRI/SPring-8, Hyogo-ken

Central Japan Synchrotron Radiation (SR) Research Facility is under construction in the Aichi area, and the service will start from FY2012. Aichi Science & Technology Foundation is responsible for the operation and management, and Nagoya University SR Research Center is responsible to run the facility and support the users technically and scientifically. The accelerators consists of an injector linac, a booster synchrotron and an 1.2 GeV electron storage ring with the circumference of 72 m. To save construction expenses, the 50 MeV linac and the booster with the circumference of 48 m are built at inside of the storage ring. The beam current and natural emittance of the storage ring are 300 mA and 53 nmrad. The magnetic lattice consists of four triple bend cells and four straight sections 4 m long. The bending magnets at the centers of the cells are 5 T superbends and the critical energy of the SR is 4.8 keV. More than ten hard X-ray beam-line can be constructed. One variable polarization undulator will be installed in the first phase. The electron beam will be injected from the booster with the full energy and the top-up operation will be introduced as early as possible.

• S. Koda, Y. Iwasaki, T. Kaneyasu, Y. Takabayashi
  SAGA, Tosu

Saga Light Source (SAGA-LS) is a synchrotron radiation facility with a 255 MeV linac and a 1.4 GeV storage ring. The spectral range covers from VUV to hard X ray region of about 23 keV. Improvement and development of the accelerator have been achieved from official opening of the facility. Stored current of the storage ring has been increased from 100 mA to 300 mA in these three years. An APPLE-2 undulator was developed and installed to a long straight section LS3. A field correction system for the undulator was developed to compensate precisely betatron tune shift, dipole kick and skew quadrupole. A superconducting wiggler is under construction. The peak field and critical energy are 4 T and 5.2 keV, respectively. The wiggler will provide synchrotron radiation in the 20-40 keV range. The wiggler consists of a superconducting main pole and two normal conducting side poles. The main pole is directly cooled by a small GM cryocooler and liquid helium is not used. In addition, laser Compton scattering experiment is under progress. A port to introduce CO₂ laser light was installed as a beam line BL1. First gamma ray was observed in December 2009.

• T. Kaneyasu, Y. Iwasaki, S. Koda, Y. Takabayashi
  SAGA, Tosu

An APPLE-II type variably polarized undulator was installed in the SAGA-LS storage ring in 2008. Following the installation, we have investigated influence of the undulator on the electron beam. Based on the measurements, we have developed a feedforward correction system to minimize the effects of the undulator. The correction system successfully compensates for closed orbit distortion (COD), betatron tune shift and a weak change in the betatron coupling. The standard deviation of the COD variation relative to the reference orbit and the tune shift are suppressed to less than 4 micron and 0.001, respectively, when the pole gap is changed at a fixed phase. The observed tune shift is interpreted in terms of a second order focusing effect evaluated by RADIA code. The simulated tune shift fairly agrees with the measurements. To minimize the effects on the betatron coupling, a wire-type skew quadrupole magnet mounted on the undulator duct is utilized. The skew field required for the coupling compensation is consistent with those predicted by field integral measurements. The feedforward correction reduces the effect to a relative change in the vertical beamsize of 5%.