MAGNETIC FIELD MEASUREMENT OF QUADRUPOLE MAGNETS FOR S-LSR

The magnetic field measurement of the quadrupole magnet for the compact ion storage ring, S-LSR, is presented. To investigate the magnetic flux at the interspace of the quadrupole (QM) and bending magnet (BM), the QM magnet field measurement by a Hall probe is carried out together with the field clamp and BM for S-LSR The direct measurement of the integrated field gradient error by the twin coil is studied. Then, obtained results by using twin coil (the horizontal distribution of the integrated field gradient and the higher order coefficients) will be presented. QUADRUPOLE MAGNETS FOR S-LSR S-LSR is a low energy ion storage/cooler ring consisting of a circumference of 22.557 meters, a superperiodicity of 6, a straight section length of 1.86 meters, and a magnet rigidity of 1.0 Tm. The scientific programs for S-LSR are an electron cooling of a laser-produced ions and a realization of a crystal ion beam [1]. S-LSR has 12-QMs with a bore radius of 70 mm, a maximum field gradient of 5 T/m, and a magnet length of 200 mm. By requirements for the small ring accelerator, distances between accelerator components at the arc sections are very short as shown in Fig.1 (a). The distance between a bending magnet and QM is 200 mm. To suppress and control a magnetic flux in a fringing field of a BM, a field clamp with a thickness of 25 mm was installed in between BM and QM. The distance between the field clamp and QM is 80 mm. as shown in Fig. 1 (b). The 3D calculation for QM represented that the QM field is strongly influenced by the field clamp. Therefore, QMs were designed and optimized in considering the influence of the field clamp [2]. Table 1 lists the specifications of QM for S-LSR