Vacuum interrupter with arc diffusing contact design

A vacuum circuit interrupter has a coil for generating an axially oriented magnetic field to maintain an electric arc in a diffuse rather than columnar mode upon opening of the interrupter. At least one of two electrodes having abuttable disc shaped contacts is movable along an axis relative to the other and can be forced by an external mechanism to open. The electrodes are carried in a housing with an electrical insulator between opposite end mountings that support the electrodes with the contacts in an evacuated enclosure. One of the electrodes is an assembly including a rigid supporting member attached to one of the contacts and extending a length along the axis. A coil is wrapped circumferentially around the supporting member along this length, providing a conductive path to generate the axial magnetic field. The supporting member comprises a less-conductive path (e.g., a stainless steel sleeve) and the coil is more conductive (e.g., copper), providing a durable and inexpensive structure.