Diamond Fast Opening Breaking Switches

184 Diamond Fast Opening Breaking Switches--Alameda Applied Sciences Corporation, 2235 Polvorosa Avenue, Suite 230, San Leandro, CA 94577-2249; (510) 483-4156 Dr. Rahul R. Prasad, Principal Investigator Dr. Mahadevan Krishnan, Business Official DOE Grant No. DE-FG03-97ER82320 Amount: $74,989 Alameda Applied Sciences Corporation will develop a fast-opening breaking switch to improve the heating of plasma in a fusion reactor based on radiation-induced conductivity in diamond. For radiofrequency heating of fusion plasmas, breaking switches must conduct high currents and hold off very high voltages (approximately 100 kilovolts) when opened rapidly in inductive energy store circuits. Solid-state breaking switches presently available consist of stacks of gate turnoff thyristors connected in series since a single thyristor can hold off only 2-5 kilovolts. Such an arrangement is complicated because of the requirement of floating gate turnoff circuitry. This project aims to develop a single diamond switch that could replace a large series stack of silicon-junction switches. During Phase I, a proof-of-principle switch will be constructed to hold off 10-kilovolts when open and conduct at least 1 kiloampere per square centimeter when closed. This switch will close upon the application of an electron beam trigger and open when the beam is extinguished. After the concept validation in Phase I, a full-scale prototype capable of holding off approximately 100 kilovolts and conducting 1-10 kiloamperes will be validated in Phase II. Commercial Applications and Other Benefits as described by the awardee: This class of switches will find potential application in a variety of switching applications including: Fast-opening breaking switches for radiofrequency heating of fusion plasmas; solid-state circuit breakers for the power distribution industry; fast-opening switches for inductive energy store; and x-ray, electron and ion beam accelerators. The related closing switches will find application in power distribution, electric aircraft, ships and vehicles, to name but a few applications. _