Electric insulation in bath cooled superconducting magnets with bare conductors

Electric insulation of bare superconductors in bath cooled magnets is a requirement for safe operation of such magnets. Electric insulation of such conductors is accomplished by spacer constructions. The authors consider a spacer construction which is built up by spacer bars attached to a straplike girder mounted in a slot of the conductor surface. Typical electric load at these spacers can be defined as flash over load. Different operating conditions of the coil drive the cooling fluid into various states, in which electric insulation must sustain the possible ultimate voltages at the coil. The insulation system of a large dipole is described. Experimental performance of the insulation system is outlined at different temperatures of the cooling helium. The test equipment and experimental results are described and discussed.<>