High repetition rate charging a Marx type generator

Summary form only given, as follows. Resistive ladder networks are commonly used as the charging and isolation means for Marx-type high voltage generators. The resistive charging network, however, suffers from several serious limitations. Namely, the efficiency is limited to 50% and the long charge time limits the PRR (pulse repetition rate). The efficiency can be considerably improved by replacing the resistive ladder with inductor elements; however, the PRR is only slightly improved. In this paper it is shown that by introducing mutual coupling, k, between the two parallel inductors in each stage of the, ladder network, the effective inductance during the charging mode is decreased by a factor of (1-k)/(1+k). Since it is feasible to achieve a coupling, k, on the order of 0.99, this speeds up the charging time by about an order of magnitude compared to resistive or conventional inductive charging. During the erected or discharge mode, the inductors provide isolation between stages and must not excessively rob energy from the energy store. The addition of mutual coupling is beneficial because during the discharge cycle, the effective inductances of the ladder elements are actually increased by a factor (1+k). The Marx switches cause a re-arrangement of the coupled inductors from parallel during the charging to series during the discharge modes. This results in a much faster charging time, by reducing the effective inductance by (1-k)/(1+k); while providing an effective isolation inductance that is (1+k) greater than the uncoupled value. The practical design of the coupled inductors for high voltage applications is discussed and modeled simulations of the performance are included.