Design of a Compact 1-MV-Class Radial Closing Switch for Tesla Type Generator

The paper presents the development of a megavolt-class SF6-insulated radial switch. The switch is used as a crowbar in a MV Tesla-type generator to produce pulsed electric fields in very large volumes, for proof-of-concept experimentation of a novel non-invasive food processing technology. The main features of the switch include: (1) Using SF6 gas as the insulation gas; (2) a breakdown channel along the radial direction, rather than axial; (3) a compact configuration with its volume limited to 3.2 L. In order to achieve a ruggedized high voltage insulation as well as an enhanced operation safety, the following design techniques were applied: (1) Structures of the switch were well designed to minimize the local electric filed in the cathode triple junctions; (2) the grooves of surface of the insulators that enclose the switch were finely optimized to keep the surface flashover under control; (3) a prolate spheroid geometry of the high voltage electrode was adopted to achieve a better control of the gas breakdown. This paper describes in detail the design and the preliminary test of this switch.