Mission

The insertion device (ID) is an apparatus to generate a periodic magnetic field and is installed in the straight section between adjacent bending magnets. An electron moves along a periodic orbit in the ID, which results in a much higher brilliance of synchrotron radiation (SR) due to coherent sum of radiation emitted at each period. Especially, an ID called an undulator is well suited to a light source in a SR facility such as the SPring-8 having an electron beam with a high quality (low emittance), because the beam size and angular spread of SR emitted from the undulator is quite small. The ID team is in charge of designing, construction, maintainance, and administration of IDs for SPring-8 beamlines together with development of novel IDs.

Activities

All the IDs that have been installed in the SPring-8 storage ring have exotic characteristics. Refer to the followings.

In-vacuum undulator(BL09XU,BL10XU,etc)

In conventional IDs, a vacuum chamber is installed between top and bottom magnet arrays. On the other hand, the magnet arrays are installed in the vacuum chamber in the in-vacuum undulator, which realizes a magnet gap much narrower than that is achieved by the conventional ID. The 1st in-vacuum undulator has been constructed in KEK, and many improvements have been made for standardization at SPring-8. Nowadays, the in-vacuum undulator concept has spread throughout a large number of SR facilities all over the world.

Helical undulator(BL25SU)

The helical undulator is an ID that generates a helical magnetic field to let an electron move along a spiral orbit and emit circularly polarized radiation. In SPring-8, a helical undulator composed of three magnet rows for each (top and bottom) magnet array has been proposed and constructed for BL25SU, in order to improve the uniformity of the magnetic field along the horizontal axis and to suppress the degrataion of the degree of circular polarization due to gap change. In addition, two helical undulators of this type have been installed tandem together with five kicker magnets to realize a fast switching of circular polarization.

Figure-8 undulator(BL27SU)

The figure-8 undulator is an ID to reduce the heat load on optical elements. An electron moves along an orbit that looks a figure of eight when projected onto a transverse plane. In addition, it provides horizontal and vertical polarization simultaneously.

Besides the development of the above IDs, investigations on demagnetization of permanent magnets due to electron beam irradiation have been carried out in the framework of a collaboration with PAL (Pohang Accelerator Laboratory: Korea).