ICRF DCC Solid State Transmitter

Recent advances in fusion technology are accelerating the development and integration of commercial fusion devices. In order to maintain controlled fusion reactions, the plasma must be heated to great temperatures and efficient current drive must be established. The Ion Cyclotron Range of Frequencies (ICRF) have been demonstrated to be effective for these purposes, and for high magnetic field devices, 60-240 MHz radio frequency (RF) systems are envisioned. Conventional vacuum electron device (VED) RF sources have a high life cycle cost with frequent maintenance, a large footprint, poor efficiency, and a fragile supply chain. Additionally, current solid-state solutions face similar footprint, costly combining and cooling obstacles that are resolved in DTI’s solid-state approach. Beyond fusion, the work completed in theses DOE efforts has close synergy with VHF radar systems, such as the ARPA Long-range Tracking and Instrumentation Radar (ALTAIR) in the South Pacific Kwajalein atoll and could be a substantial upgrade to expand radar capabilities. This proposal addresses the development of a scalable, solid-state Direct Cavity Combiner (DCC) that hundreds of identical RF modules into a high-power RF source. The approach constitutes the design and fabrication of a 500 kW SSPA for pulsed peak power testing, as well as a Continuous Wave (CW) demonstration at 100 kW to show scalability of the DCC to megawatt levels. The DCC offers high power density as well as a simple and efficient combining scheme, that greatly reduces cost. Some added benefits are the high efficiency of solid-state devices, improved life cycle, and modularity of devices for replacement and upgrades. In Phase I, a partial population of 31 modules generated an RF output of 43 kW at 81% efficiency on the full-scale 120 MHz cavity to demonstrate efficient scale-up. Phase II will utilize the Phase I cavity, improve it, and iteratively improve the performance and increase the number of modules. The work will be performed in stages to build greater and greater numbers of modules, increasing the peak output power iteratively. The further development of the DCC technology will address the large combining footprint, complexity and high costs associated with conventional SSPAs or VEDs. The application of this advanced architecture lends itself well to fusion ICRF, VHF radar transmitters, and high-energy physics experiments.