Components for Heating and Fueling of Fusion Plasmas

Next generation fusion facilities will require many megawatts of RF power from dozens of gyrotrons. Conventional DC power systems, built from WWII era components, have provided the typical approach to powering high-power RF vacuum devices for the last 50 years. Typically, they suffer from reliability and availability problems, and are often only 50 70% efficient. Scaling these conventional RF power electronics for next generation high power fusion facilities is not practical in terms of cost or reliability. Fortunately, the last decade has seen the development and rapid adoption of solid-state, high voltage power electronics. This SBIR effort proposes to develop a Buck Matrix modulator, a unique single set of switches that delivers voltage regulation, arc protection, and pulse modulation to future fusion facilities. This topology, with an estimated efficiency of 96%, cuts the size of the traditional power system in half, using a single layer of solid state switches for both voltage regulation and arc protection / modulation. The Phase I effort successfully analyzed and modeled the Buck Matrix configuration in both the full size and Phase I demonstration configurations. A representative, scaled version of this novel configuration of multi-phase series and parallel arrayed solid-state buck regulators wasdeveloped and bench-tested. The simulations and experimental results show that the full sized Phase II system is feasible, in terms of cost, size, performance, and manufacturability. A preliminary high voltage and mechanical design of the full sized Phase II prototype was made. In Phase II, a full scale demonstration unit will be built for delivery to a west coast tube manufacturer, or a suitable US fusion facility for evaluation. Commercial Applications and Other Benefits: The resulting design is transferable to CW or long pulse applications, including future RF accelerators, light sources, and synchrotrons, and other DOE programs, such as the International Linear Collider (ILC). Applications beyond the fusion community such as Active Denial, and previously unworkable industrial applications of high-power gyrotrons, will now be open to exploration.