Transmitter and HVPS Architectures in the Ion-Cyclotron Radio Frequency System of DTT

The design choices for the conversion of electrical energy into radio frequency (RF) waves is critically reviewed in this paper to conceive the most suitable architectures for RF transmitters in nuclear fusion. Ion Cyclotron Resonance Heating (ICRH) systems, using RF waves to heat fusion plasmas, present specific and demanding requirements in terms of power supplies that are tackled here with reference to the DTT, a new advanced fusion machine currently under construction. After the selection of the technology for the amplification stages of ICRH transmitters, the electrical specifications of the power supplies are determined on the basis of several parameters such as amplification, efficiency and loading conditions. The study presented in this paper concerns the choice of the most suitable architecture of the high voltage power supplies. It is based on available literature and technical documentation as well as on the calculation of operational points for the high-power amplification stages in mismatching conditions. Several possible solutions have been analyzed but the peculiar needs of ICRH system, such as the high performance in terms of accuracy, stability and fast response, lead to the adoption of unconventional solutions, resulting in a custom design. Finally, some alternatives and improvements are proposed.