Effects of filtration on the impulse breakdown strength of high-purity water

High-purity water is the dielectric of choice for most pulsed-power machines. Increasing the electrical breakdown strength of high-purity water is one of the principle goals for pulsed power, because the energy density stored in the water increases as the square of the electric field. This paper concentrates on the impulse breakdown strength for long-stress times (i.e., greater than 65 microseconds). Previous work at Dahlgren has shown that the breakdown strength is independent of stress time in this regime. Our hypothesis is that impurities control the breakdown behavior of nominally high-purity water. Specifically, we present experimental data that shows the use of filtration methods designed to remove organic material and particulates (which don´t affect the resistivity of water), improves the breakdown strength. Earlier results that showed a time variation for improvements in breakdown strength are explained. An experimental design to achieve even greater improvements in breakdown strength is presented.