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A laboratory repetitive inductive storage power supply (ISPS) for the ignition of an electrothermal-chemical (ETC) gun is described. It is designed for delivering to an electrothermal load an energy of 400 kJ in a shot under the assumption that this energy suffices for an effective ignition of advanced consolidated propellants accounting for temperature compensation. The ISPS is battery-based. The battery has a peak power of 5 MW and is able to charge a cylindrical coil to 700 kJ. Fringe fields of the coil with and without ferromagnetic screens in static and transient conditions are analyzed using numerical simulation. A conclusion is drawn that a screen of reasonable weight cannot reduce the stray field below a susceptibility level of electronic devices that should be shielded individually. A hybrid repetitive opening switch (OS) rated 50 kA, 4 kV, 70 μs breaking time is described. A commercial vacuum circuit breaker serves as the first stage. At a desired moment, it is opened, and the current is transferred to the second stage, which is an integrated gate-commutated thyristor (IGCT) that finally breaks the current. The IGCT turnoff is assisted by an inverse current injection into the second stage. The main benefit of this technique is a dramatic reduction (by a factor of ten) in the quantity of semiconductor devices in the second stage. The OS design, assisted by PSpice simulations coupled with field analysis of nonlinear magnetic components is described. Test results are presented. Overall, this work supports an earlier conclusion that an 0.5-MJ ISPS, capable of delivering the first round of an eight-shot burst in 0.3 s, will occupy 0.6 m3 net volume and weigh 1000 kg.