Real-time MHD feedback control system in Keda Torus eXperiment

Abstract

This article describes the feedback control system in magnetic confinement devices, aiming to mitigate magnetohydrodynamic (MHD) instabilities and optimize plasma confinement within the Keda Torus eXperiment (KTX). The system includes saddle sensors as the input signal, a real-time control system as the core controller, a digital power amplifier (DPA) array as the actuator, and saddle coils as the brake to restrain the MHD instabilities. A flexible, distributed real-time control system based on field-programmable gate array (FPGA) has been developed and implemented for MHD control in KTX. This is the first time FPGA has been used to verify presupposed magnetic field mode, perform data acquisition, real-time calculation, and real-time feedback in KTX. It fulfills the real-time requirements of the experiment completely. The system is presently utilized in MHD control experiments, successfully achieving experiments at the current stage that reach the limit of Ohmic discharge, with good reproducibility.