科研之友
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摘要
With the advances made in accelerator technologies, particle accelerators are being employed in a wide range of fields such as physics, biology, and medical treatment. However, the diameters of the main rings in most accelerators are large; for example, even the smallest carbon cancer therapy accelerator has a main ring diameter of approximately 20 m. Since a rotating gantry for a carbon-ion beam is also very large compared with the gantry for a proton beam, widespread adoption of this therapy system has been restricted. In order to promote widespread adoption of carbon cancer therapy accelerators, it is necessary to reduce the bending radius of the carbon-ion beam. One way to achieve this is to use superconducting magnets with higher magnetic fields. High-T-c superconducting (HTS) magnets have higher thermal stability and need lower power consumption for cooling than low-T-c superconducting (LTS) magnets. Although saddle-shaped coils are suitable for accelerator magnets, an HTS conductor has anisotropic bending flexibility because of its tape shape. To evaluate winding technologies for HTS saddle-shaped coils, a number of coils were fabricated and tested. The test coils were about 400 mm long and 160 mm wide. Each test coil was wound using an approximately 45-m-long 4-mm-wide YBa2Cu3Ox (YBCO)-coated conductor. Some of the coils were excited to measure their voltage-current characteristics in liquid nitrogen. An index value over 20 was obtained throughout an electric field range down to 10-7 V/m, which indicated that the superconducting properties would not be degraded. To evaluate the quality of the magnetic field distribution and the thermal stability of a conduction-cooled HTS magnet, we fabricated and tested an HTS magnet consisting of eight saddle-shaped coils.
- 出版日期2015-6
