In most cases we have applied special Marx-generators for the production of the high voltage pulses required by our applications. Marx-generators are built from high voltage capacitors which are charged in parallel and rapidly discharged in series by closing of switches between capacitor stages. Consequently the output voltage corresponds to the charging voltage multiplied by the number of stages. A real advantage of this configuration is its modularity and its ability to cover a wide range pulse amplitudes. Critical for the generator economy are cost and lifetime of their components. We have been using pulse capacitors for which the vendor warrants a lifetime of 10⁹ pulses corresponding to a 3 year operation at 20 Hz. Besides the capacitors the switches are the next important component. Because of their simplicity and robustness we have preferred gas filled spark gaps over semiconductor switches. Spark gap electrodes are subject to a certain burn-off changing their switching voltage. To keep the effect of this wear within economically acceptable limits we have developed special CuW-electrodes whose profile and diameter guarantee a sufficiently slow and homogeneous burn-up. In addition the switching voltage can be kept constant by adjusting the gas pressure and the gap distance. All spark gaps are housed in a common switch tower cooled by a gas stream and containing filters to remove the burn-up particles. At the FRANKA-facilities the work electrode is an element of large wear and practical concepts for tracking have to be developed. To protect the insulator surrounding the work-electrode against destruction a special profile to reduce the fields at the triple point where water, metal, and insulator come together have been developed and patented.

To achieve the required high throughput in industrial applications several Marx generators must be operated synchronously and ignited at the same time. This requires a low wear trigger system with small jitter for each generator. Conventionally spark switches are triggered by a third electrode. Such configurations possess a large burn-up and therefore cannot be applied. For this reason we have developed and patented an overvoltage triggering system with little wear. It uses the Marx-generator charging coil in the first stage as secondary winding of a pulse transformer. Triggering is achieved by superposing a voltage pulse on the charging voltage existing across the switch electrodes.