Design and testing of a magnetically operated rep-rate opening switch

A magnetically operated opening switch was designed to divert current from an inductive store into an electromagnetic launcher. The switch was designed to be operated repetitively on command (i.e., noncyclically). A laboratory development switch was designed, fabricated, and extensively tested to determine electrical and mechanical operating properties. The switch has been repetitively tested with contact currents as high as 30 kA, corresponding to contact current densities of 500 MA/m². Opening times of less than 300 microseconds are regularly observed. The switch can also be used to shunt current from the launcher when desired projectile velocities have been achieved, thereby conserving inductor energy. Closing times of 200 microseconds were observed in this mode. The effects of lead impedance on opening characterisitics are reported.