Repetitive 600 kV vacuum insulator testing system for insulator areas on the order of 10/sup 3/ cm/sup 2/

Summary form only given. Vacuum insulators are a crucial component of most pulsed power drivers and their reliable operation is key for many machines. The desire to run these machines at higher energies often pushes the limits of these insulators and a solid understanding of their behavior is crucial for future designs. Finding insulator configurations that can perform reliably under higher stress will reduce the cost and size of many pulsed power drivers and allow for higher energy testing. For these reasons, a Vacuum Insulator Tester has been built to better understand the behavior of these insulators. The Vacuum Insulator Tester is comprised of a 600 kV Marx generator submerged in transformer oil and a cylindrical vacuum chamber 1.0 m in diameter and 0.4 m deep. The Marx is computer controlled and can be shot repetitively while unattended. In addition, the voltage output can be varied between 100 kV and 600 kV. Currently, the test stand will be used for two different experiments. One experiment is to collect data on the effect of stacked insulators versus single insulators of equal area in probability of surface flashover. The second experiment, is to determine the lifetime of a stressed insulator before a breakdown in the bulk material occurs. Vacuum insulators having a 45-degree slope on the exposed surface are commonly used to increase breakdown strength. These insulators have field enhancements at both the anode and cathode triple points that can be lessened by reshaping the conductors on either side. However, while an anode plug design can reduce the peak field at the anode triple point, it also increases the field in bulk of the material and may eventually lead to a breakdown of the bulk material. The experiment will help determine the lifetime of the bulk insulating material (Rexolite) under high field stress. Similar testing is concurrently being done, but such experiments lack the high daily shot count that this system can provide. Also, the tested area of 10/sup 3/ cm/sup 2/ will allow for more accurate scaling to larger situations.