Optimizing Compact Marx Generator Networks for Charging Capacitive Loads: Sequential Triggering and Practical Considerations

Efficient pulse charging of small high-voltage capacitive loads with Marx generators is limited by the parasitic capacitance of the Marx network. Yet stray capacitance to ground can not be much smaller than the inter-stage capacitance for proper Marx erection. In earlier work, Marx network designs were found that transferred energy with perfect efficiency [1][2]. Ideal network designs were determined by constraints imposed by energy and charge conservation, and by waveform and resonant frequency symmetries. Lossless linear networks that transform Energy between states of purely magnetic and/or purely electrostatically stored energy must exhibit waveforms that are periodic in time [3][4]. The final step involves the assignment of the network resonant frequencies to the fundamental and only even harmonics of the fundamental. Simultaneous switch closure is also required. For regular network solutions, only the lower-order harmonics possess appreciable energy, and suitable approximate solutions may be found by ignoring the higher-order resonant modes and allowing stray capacitances to possess common optimal values. Sequential Marx-switch triggering produces a mixed initial state that compromises the viable solutions. The few percent of energy remaining induces high frequency oscillations in the circuit that could lead to early component failure. Correction attempts have had limited success except for mid-stage Marx triggering, which shows significant benefits. Simultaneous laser triggering is a promising ultimate solution to this problem [5].