First Experimental Characterization of the Magnetic Energy Storage and Transfer (MEST) System

Abstract

The magnetic energy storage and transfer (MEST) system is a technology conceived to address the issues of high active power transients and huge reactive power demand of conventional coil power supplies (CPSs), thus providing an effective solution to be employed in future large fusion reactors. The MEST system exploits an additional superconducting coil sink coil (KC) as an energy storage to sustain the operation of the load coil (LC). Through a switching section and a capacitor bank, it is able to transfer energy bidirectionally between the two superconducting coils, to provide the required current to the LC. Thanks to this storage, the external AC grid must supply only the average power through a power supply (PS) that charges the KC. A small-scale prototype of the MEST system is nearing completion, serving as a proof of concept and enabling the investigation of scaling the design to higher power ratings. The prototype operates with a resistive sink and LCs and follows a modular approach for the switching section (combined with the capacitor bank), with two modules in total. The modules are designed for operation at 2 kV and 2 kA and can function independently or be connected to achieve higher ratings. This prototype will permit the evaluation of the advantages and limitations of the specific topology, examine various configurations, test different control strategies, and understand any unexpected experimental findings. The first tests focus on verifying the prototype’s functionality, particularly the integration of the components, and assessing the system’s ability to effectively control the currents in both coils. This work presents the results of the initial tests, the first characterization of the circuit, and the validation of the developed numerical models with experimental data.