Noise reduction of Marx generator erection

An experiment has been designed to measure charge injection into insulators using high voltage pulses. In order to limit the area of charge injection, point plane geometry and low energies are used. These low energies are achieved by using a small Marx generator, a ring up inductor and a vacuum feedthrough bushing and insulator sample to provide a CLC ringup. Connecting the ground plane behind the sample introduces a second inductance which produces a second mesh in the equivalent circuit. Charge injection into the insulator provides a short risetime pulse which excites the second mesh. Monitoring the excitation of the current in this second mesh provides charge injection information. The erection of the Marx generator via spark gaps is a source of high frequency electrical noise which also excites the second mesh and therefore must be reduced if charge injection information is to be obtained. Inserting ferrite cores of proper frequency response between stages of the Marx generator, as well as on both sides of the ring up inductor, is shown to reduce the erection noise. This noise reduction is demonstrated by a decrease in the excitation of the high frequency resonant mesh. With the ferrite cores inserted the amplitude of the second mesh excitation is 20% of what it is without the ferrites.