Design and construction of a two-stage opening switch

Electrical and mechanical design features are presented for a two-stage opening switch for use in charging inductive capacitors from megajoule output homopolar generators. The first stage consists of a massive mechanical part with a coaxial geometry and many low resistance galvanic contacts. Commutation is realized by a low inductance to a second stage that is interrupted explosively to provide the required microsecond commutation. Design and theoretical considerations which allowed for heating under the switch contacts, the peak constriction current force the contacts would encounter, and energy dissipation required of the contacts in inductively transferring energy to the second-stage switch are summarized.