Development of radiation-resistant magnet coils for high-intensity beam lines

In connection with the Japanese Hadron Facility (JHF) project, the development of new types of radiation-resistant magnet coils has been continued at KEK. One major program is the design and production of a mineral insulation cable (MIC) with a larger maximum current. The authors have already developed a 2,000A-class MIC having a square-cross-section hollow conductor. A sample magnet coil was fabricated with this MIC. Tests of its stability and reliability are under progress. The authors are now planning to develop a 3,000A-class MIC. The other program is R/D work on a completely inorganic wrapping insulation material which can be used like the usual type glass-fiber tape pre-impregnated with epoxy-resin. After tests of the mechanical strength and electric insulation of many combinations of tapes and bonds, they found a pure (99% >) alumina-fiber tape pre-impregnated with inorganic cement that is suitable for a magnet coil insulator after thermal curing