The invention concerns a method for repeatable ignition of propellant charges in a weapon system, e.g. for firing shells from a barrel weapon, through electrical discharge in a combustion chamber duct (3) containing a combustion chamber substance (30), wherein the filling gas in the combustion chamber duct (3) is ionized by the high-voltage potential applied to the ionizing electrode (7), which is connected to a first high-voltage generator (2), thus increasing the electrical conduction capacity in the combustion chamber duct (3) such that an electrical sparkover through electrical discharge via a second high-voltage generator (5) between a rear electrode (22) and a front electrode (21) is generated and produces an effect, with subsequent ionization of the surface of the combustion chamber substance (30), which causes hot gas in a plasma-like state to be expelled from the combustion chamber duct (3). The invention also concerns a plasma generator therefor, and an ammunition unit containing said plasma generator.