Abstract: Pulse stability is provided to a pulsed gas filled electrical discharge device by an electrical circuit including first and second electrical energy storage means, with the energy stored in the first storage means being substantially greater than the energy stored in the second storage means. A first voltage corresponding to the energy stored on the first storage means is applied to the input of the gas filled device. A second voltage corresponding to the energy stored on the second storage means is periodically switched to combine with the first voltage and be input to the gas filled device. The period for switching is precisely controlled, preferably with a piezoelectric crystal, and is selected to combine the first and second voltages just before the first voltage reaches the natural breakdown voltage of the gas within the gas filled device.