A self-resonant plug-in IC antenna for DTT

Ion Cyclotron Range of Frequencies (ICRF) antennas are adopted in most of the existing nuclear fusion experiments. Their capability to couple high power to the plasma is known to be limited by a high input reflection coefficient and sometimes by high electric fields within the antenna box and immediately in front of it. In this work, we introduce a self-resonant IC strap antenna that can reach very good impedance matching, i.e. with very small power reflected back to the feeding lines; it is designed for the incoming Divertor Tokamak Test (DTT) experiment [1]. The antenna reaches matching for a bandwidth limited by the electrical size of the box, that is not compatible with operational planned frequency interval. Hence, we also propose an all-metal frequency structural tuning system; this allows launcher to be operated in frequency intervals of practical interest, e.g. from 60MHz to 90MHz. The overall antenna is a two-strap plug-in launcher that fits within DTT equatorial duct. After introducing the antenna concept, we describe a few optimization steps carried on through numerical codes, with a specific focus on the critical aspects mentioned above.