Switching considerations and new transfer circuits for electromagnetic launch systems

Electromagnetic (EM) launchers have severe switching requirements. Switching demands for railgun systems, for instance, include current conduction from hundreds of kA to a few MA, conduction times of a ms to a few s, standoff voltages as high as a few tens of kV, recovery voltages of 1-10 kV after conduction, opening and closing duty, and repetitive operation up to about 50 Hz. These demands, particularly for repetitive opening duty, are far beyond the capability of most current switches and switching concepts. This paper will review the performance of rod array triggered vacuum gap (RATVG) switches and discuss their potential for solving switching problems in EM launcher systems. A new mode of operation for the RATVG switch is proposed. Fundamental considerations for the operation of opening switches and their associated transfer circuits are presented. Methods of recovering the railgun's inductive energy to enable efficient repetitive operation are discussed and new circuits with such capability are proposed.