Real-time data processing method for the feedback control system of the error field of the Keda Torus eXperiment around the gap

This article describes the feedback control system of the error field in a reversed field pinch (RFP) device KTX. The system includes an electromagnetic probes(EMP) array, a real-time control system based on a field-programmable gate array (FPGA), a digital power amplifier (DPA) array as the actuator, and a feedback control coil. It takes full advantage of FPGA to fulfill a highspeed, real-time feedback control requirement. Zero drift elimination and real-time PID on FPGA make real-time feedback control possible. It successfully achieved the mission of error field control and made the magnetic field density drop more than 90 percent.