An evaluation of dielectric materials for use in pulsed power devices

In order to improve the high voltage performance of pulsed power equipment a study has been undertaken into the dielectric strength of various liquids, gels and solids. The experimental set-up for this investigation used an 8 stage Marx generator in order to produce a high potential difference between two uncoated stainless steel spherical electrodes. The electrodes were insulated by the material under test and were spaced 1.5 to 3.5 mm apart. The breakdown voltage of each of the samples was recorded as a function of the gap distance, and the data was then post-processed in order to determine the breakdown strength of each of the materials. A number of substances were identified that had very high breakdown strengths and these are now being incorporated into our pulsed power devices. In addition to these tests, investigations were also undertaken on oil insulated electrodes coated with a variety of dielectric materials. A number of coatings were identified which were capable of increasing the breakdown voltage by up to 60% over uncoated electrodes. Additional results were taken for a selection of coating materials in order to evaluate the effect of coating thickness and storage temperature on the breakdown voltage performance.