In order to decouple the low-voltage charging source and its electrical drive from the high voltage which occurs in a Marx generator when the capacitor bank is switched from parallel connection to series connection, the high-voltage cable which is used on the output side and in which the conductive core is surrounded by a semiconductor for potential matching is also used on the input side, but for high-voltage decoupling after removal of the current-carrying core. Only the semiconductor in the high-voltage cable therefore remains as a resistance line for the small charging current into the parallel-connected capacitor bank of the Marx generator.