Real-time resonant magnetic perturbations feedback control system for tearing mode suppression on J-TEXT

Abstract

Tearing Modes (TMs) degrade the performance of tokamak plasma, and can even lead to disruption. Using externally exerted resonant magnetic perturbations (RMP) to suppress tearing mode is a promising and effective way. In order to suppress 2/1 tearing mode, 2/1 RMP applied in given phase region to stabilize magnetic island and accelerate island rotation. The RMP feedback control system acquires 15-channels Mirnov poloidal signals, processes the acquired data and calculates the phase in real-time; outputs RMP power supply control signal by comparing with the given phase to drive RMP coil. The feedback control system is based on NI C-RIO and mainly using LabVIEW to develop. The typical 2/1 mode magnetic island on J-TEXT rotates at a frequency from 2 KHz to 10 KHz. To ensure the control precision within 2 degrees, the control period must be within 500 ns. Due to acquired signals are noisy, the feedback control system uses a series of error correction methods in realtime to obtain accurate phase.