Optimizing compact Marx generator networks

Compact linear Marx generators are frequently constructed in close-fitting metallic housings. The parasitic capacitance formed between the enclosure and Marx components can substantially exceed the inner-stage capacitance and play an important role in the Marx network performance. This capacitance and the inner-stage inductance form the components of a lumped-constant transmission line, which facilitates proper sequential firing of the spark switches. With appropriate component values, these Marx generators can deliver fast rising and nominally flat pulses into resistive loads. These same Marx generators may be thought intrinsically unsuitable for charging capacitive loads because of their relatively large internal parasitic capacitance. When the total parallel parasitic capacitance exceeds the effective series capacitance of the charged capacitors, as little as two thirds or less of the stored energy may be transferred to the external load capacitor if driven directly by the Marx generator. In addition to the loss in transfer efficiency, the remaining energy induces high frequency oscillations in the Marx circuit that will lead to component heating and early failure. These problems can be avoided by suitable choices of Marx network component values, switch timing, and external network components. In fact, even with relatively large parasitic capacitance values, theoretical solutions are found for which energy transfer efficiencies of unity are achieved with lossless network components. Necessary and sufficient conditions for such solutions are presented with examples and PSpice simulations. The inception of a formal theoretical treatment of this problem is presented in a companion paper by Zaccarian et al.