DESC0024809

Statement of Problem & DOE/Public Interest: In order to initiate and maintain controlled fusion reactions sufficient for commercial power generation, the plasma must be heated to fusion temperatures of approximately 150 million degrees Celsius. For economical, steady state fusion devices, efficient current drive is also required. Ion Cyclotron Range of Frequencies (ICRF) have been demonstrated in experimental devices to be effective at both plasma heating and central current drive. For high magnetic field fusion devices, RF sources in the range of 40-240 MHz are required, a range of frequencies which are ideal for solid- state devices. This technology will improve RF performance compared to conventional Vacuum Electron Devices (VEDs) and conventional solid-state sources. It is in the publicĺs interest for DOE to develop commercial fusion as a practical energy source. High power RF sources are a key enabling technology for fusion heating and current drive. Advances in this technology will greatly benefit the entire fusion industry. How the Problem Will Be Addressed: High Power RF will be generated by directly combining the output of large quantities (potentially 1000 or more) solid state RF amplifiers into a single high-power output within a tuned cavity, thus eliminating the external combiners and their losses used in conventional solid-state amplifiers. This effort will build on the Direct Cavity Combiner (DCC) work that was previously performed, demonstrated, and patented at DTI, addressing module enhancements identified in DTIĺs previous work. This will be based on theoretical design, numerical analyses, and hardware fabrication and will demonstrate scalability to megawatt power levels. This will be based on previous successful DCC demonstrations at 120 MHz in the previous Phase I, as well as the 650 MHz and 1300 MHz designs. Phase I Work: In Phase I, DTI will make critical improvements to the transistor modules that are the core of the DCC transmitter to clearly demonstrate scalability to megawatt power levels. The cavity and modules will undergo test and evaluation to compare the amplifier performance to that predicted by the simulations and calculations performed as part of the design effort. Commercial Applications and Benefits: The DCC transmitter can reduce the cost of high-power RF for fusion and similar plasma heating applications. The basic transmitter technology can be readily tailored to a wide range of frequencies which makes it applicable in a wide range of applications including high energy physics, radar, and broadcasting.