Conceptual Design of the DTT ECRH High Voltage Power Supply System

The Divertor Tokamak Test (DTT) facility is a controlled thermonuclear fusion device, whose construction has started at the ENEA Research Center in Frascati, Italy, with the aim to study solutions to mitigate the issue of power exhaust in an integrated environment and operating conditions relevant for future fusion reactors. A power of 45 MW to the plasma is foreseen and provided by a mix of heating and current drive (HCD) systems comprising electron cyclotron resonance heating (ECRH), ion cyclotron resonance heating (ICRH), and neutral beam injector (NBI). DTT, in the first experimental phase, will exploit the ECRH system, including 16 radio frequency (RF) sources (gyrotrons) with potential collector depressed, each rated for 1 MW power, 170 GHz frequency, and 100 s pulse length. The RF sources are fed in pairs by a high voltage power supply (HVPS) set, composed of one main power supply (MPS) and two body power supplies (BPSs), one for each gyrotron, and by low-voltage (LV) power supplies dedicated to the operation of the auxiliaries of the gyrotrons. This work describes the conceptual design of the HVPS system, the evaluation that led to the definition of its main requirements and to the selection of a reference design. In addition, the novel concept is presented for a dummy load (DL) able to mimic the real gyrotrons operation in normal and abnormal conditions for testing an HVPS set.