P01

光源

Research and Development of Magnet for HiSOR-II
Y. Lua, M. Shimadac,a , H. Miyauchic,a, and M. Katoha,baHiroshima Synchrotron Radiation Center, Hiroshima University, HSRC, Higashi-Hiroshima,Hiroshima 739-0046, Japanb
Institute for Molecular Science, Okazaki, IMS, Aichi 444‑8585, Japanc
High Energy Accelerator Research Organization, KEK, Tsukuba, Ibaraki 305-0801, Japan

Keywords: Combined-function magnet, Hybrid permanent magnet, Energy saving

HiSOR-II has been designed as a future plan of HSRC, which will provide higher brightness VUVradiation increasing by 2 orders of magnitude compared with the present HiSOR. To reduce the construction
cost and accelerator size, the magnets in the ring lattice are being designed as combined-function magnets
which are capable of producing multipole field components, such as dipole, quadrupole, and sextupole. On
the basis of lattice parameters of HiSOR-II, we proposed two kinds of combined-function quadrupolesextupole magnets using auxiliary coil and pole profile adjustment, respectively [1, 2]. The magnet model issimulated using Radia [3], which is shown in Figure 1. In the combined-function magnet using auxiliary coil,the magnet pole profile is designed from a quadrupole magnet, and the sextupole magnetic field is generated
by a sextupole coil on the pole face and a dipole correction coil around the pole. The quadrupole magnetic
field and sextupole magnetic field can be adjusted separately. However, the structure is complicated andrequires three independent power sources. As for the magnet using pole profile adjustment, the pole profile
is a superimposition of the quadrupole and sextupole equipotential surfaces, which represents that thequadrupole and sextupole fields are adjusted in the design stage and fixed. Therefore, it is not compatible
with flexible optics that changes in the operation.

FIGURE 1. Combined-function quadrupole-sextupole magnets (a) with using auxiliary coil and (b) with pole profile
adjustment.

To reduce the operation cost, we are also considering using an electrical/permanent hybrid magnet forenergy saving [4]. The magnetomotive force is mainly generated by the permanent magnet material. The coilis assembled to provide part of magnetomotive force and adjust magnetic field strength. Such a kind ofmagnet can save the costs for electrical power. In addition, the magnet can get rid of water-cooling systemof the coil because of a low current density. However, permanent magnets are difficult to achieve highprecision and easy adjustability of the field strengths. Furthermore, there are other issues such as temperaturedependence and demagnetization caused by radiation. We also found that the existence of the PM in themagnetic circuit produces a large magnetic resistance against the magnetomotive force produced by the coil.
To solve this issue, we continue careful design study on the magnet configuration.
In order to apply the hybrid permanent magnet to HiSOR-II, the thermal effect compensation is being
studied by using a permanent dipole magnet developed at Nagoya University [5]. In the experiment, it isobserved that the variation of the dipole field strength is almost proportional to the temperature of thePermanent Magnet (PM), as shown in Figure 2.
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FIGURE 2. Variation of the By and temperature of the PM when current density is 2A/mm2.

A feedback control system for the magnetic field correction were tested. The drift of magnetic field isless than 0.0002 T (0.014%). In the future, the performance of the feedback system will be improved byincreasing the precision of the measurement of the magnetic field and temperature.

REFERENCES
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M. Katoh et al, "Upgrade plan for UVSOR," in Proc. of the 2th Asian. Part. Accel. Conf, Beijing, China, 2001.
W. Beeckman, et al, in Proc. PAC2013, Pasadena, CA USA, pp. 1229-1231.
http://www.esrf.eu/Accelerators/Groups/InsertionDevices/Software/Radia
G. Tosin, et al, Nuclear Instruments and Methods in Physics Research A 674 (2012) 67–73.
S. Fukue, et al, in Proc. of the 13th annual meeting of PASJ, August 2016, Chiba, Japan.