A LowCost, High Power RF Resonance System for Plasma Diagnostics and Heating Applications

Due to the high cost and complexity of high power radio frequency (HPRF) heating systems, which require high power gyrotrons or klystrons, associated power supplies, wave guides and vacuum systems, they are rarely available for the small scale Validation Platform Experiments (VPEs). The charter for the small scale VPE community is to advance our level of knowledge in plasma physics and control to support the larger tokomak experiments and the entrance into the burning plasma era. Significant progress in transport, instability control and the underlying plasmas physics could be gained if the VPE community had access to high power RF heating systems at costs that can be supported under current funding levels. General Statement of How This Problem is Being Addressed: Eagle Harbor Technologies, Inc. (EHT) has created new high voltage nanosecond pulser, which combined with NLTL technology will produce a low cost, fully solid state architecture for the generation of the RF frequencies and power levels necessary for plasma heating and diagnostic systems within the VPE fusion science community. The proposed system does not require the use of vacuum tube technology, is inherently lower cost, and is more robust the traditional high power RF heating schemes. The program will directly support the small scale validation experiments, where the new system will be demonstrated at two fusion experiments during the Phase II program. What was done in Phase I? In the Phase I program, EHT designed, built and tested a new high voltage nanosecond pulser system with two versions of NLTLs and associated RF antenna feed systems. The new system was demonstrated at EHT and confirmed to produce pulsed HPRF output at high pulse repetition frequency (100 kHz). EHT designed a new high efficiency lumped element NLTL. EHT also worked with both HITSI and antenna design consultants for integration of the HPRF onto HITSI. What is planned for the Phase II project? In the Phase II project, EHT plans to scale the HPRF system to higher output power levels and a build a demonstration unit, which will be utilized at both the HITSI and the High Beta Tokamak (HBT) experiments for testing and qualification. EHT will also continue development work on the novel high efficiency NLTL design to produce frequencies consistent with lower hybrid current drive applications. EHT will also work with RF antenna design experts and personnel at HITSI and HBT to properly match the HPRF to the launching antenna and to maximize RF coupling into the plasma. Commercial Applications and Other Benefits: HPRF generation using vacuum tube based systems is widely utilized in the scientific community, military and industry. Vacuum tube technology is fully mature with little expected advancement in robustness and simplicity for these systems. There is a wide need for new technologies for RF generation which can increase capabilities while reducing cost and complexity. Additionally, the new nanosecond pulser has demonstrated utility in the creation of low temperature plasmas, which have applications in surface decontamination, materials processing, UV light generation and several novel medical applications including cancer treatment. Continued support of the nanosecond pulser technology alone could have wide ranging benefits in these areas. Key Words: nanosecond pulser, high power microwaves, RF heating, nonlinear transmission line