Fluids for Dielectric Switch Applications

The Air Force has developed a fluid-filled high power dielectric switch for pulsed power applications. For optimum operation, a switch should have a nearly constant breakdown voltage or low jitter. Many factors affect the jitter, and much effort has gone into switch design to eliminate vortices and static regions in the fluid. The best fill fluid was found to be MIL-PRF-87252 polyalphaolefin (PAO) coolant. When the discharge or shot occurs; the PAO fluid breaks down into carbon and hydrogen. Reducing moisture in the fluid has been found to have a strong influence on jitter, as dramatic improvements in dielectric breakdown voltage and standard deviation happen when the fluid is sparged with dry nitrogen. Infrared analysis of used fluid that had seen 2 million shots revealed oxidation products in the C=O region, 1752.5 cm-1, and the fluid had a corresponding reduction in dielectric strength. METSS proposes to develop an improved fluid that exhibits reduced jitter based upon the mechanisms of dielectric breakdown. New materials and longer life through the incorporation of chemical additives are key approaches. The proposed program will also address additional issues related to material compatibility, personnel safety, environmental impact and use costs. BENEFIT: The development of new, successful, switch fluids will have both military and commercial uses. Military applications include modulators for high peak power electrical systems for manned and unmanned air vehicles, military radar drive circuits, directed energy systems. Commercial applications include modulators for high peak power electrical systems for high-speed rail traction, utility power distribution substations, power modulators for particle accelerators, and uninterruptible power supplies. METSS has identified potential partners to support the SBIR program development work and commercialization activities.