Improved Controls for Fusion RF Systems

Radio frequency (RF) heating systems are vital components of plasma fusion facilities. The increasing scale of present and planned fusion experiments requires a similar increase of scale of RF systems, usually involving multiple RF sources. The complex controls for these systems must manage numerous fault scenarios, monitor key signals, and interconnect key power systems to provide the required performance. At the same time, pressures of cost, space, reliability, and safety are crucial to the operation of the facility. Modernization of RF subsystems is a necessary step in advancing towards a fusion demonstration plant. This effort will target the transmitter protection circuits for a tokamak Lower Hybrid Current Drive (LHCD) RF system. The specific application of the Alcator C-Mod tokamak LHCD experiment at MIT provides a convenient target of opportunity. This modernization will coincide with the upcoming expansion of their tokamak¿s LHCD system. Under Phase I, advances in analog and programmable digital circuit design were used to greatly enhance the reliability, compactness, and safety of the transmitter protection controls. The Phase II project will fabricate and assess a suite of first article control systems, and deliver them to the C-Mod LHCD team for installation. This design will then be generalized for future availability for fusion, high energy, phased array radar, and other customers. Commercial Applications and other Benefits as described by the awardee: The result of this effort will be a template for a modernized transmitter protection system, applicable to any multi-VED (Vacuum Electron Device) RF system for a fusion or similar facility. The immediate beneficiary will be the Alcator C-Mod facility, which will use the upgraded transmitter protection system with the expanded LHCD system beginning in 2009. Non-fusion applications that use multiple VED arrays (such as phased array radars) may also benefit from these results.