Microseconds-scale magnetic actuators system for plasma feedback stabilization

Abstract

Many magnetic confinement machines use active feedback stabilization with magnetic actuators. We present a novel magnetic actuators system with a response time much faster than previous ones, making it capable of coping with the fast plasma instabilities. The system achieved a response time of 3 µs with maximal current of 500 A in a coil with inductance of 5.2 µH. The system is based on commercial solid-state switches and FPGA state machine, making it easily scalable to higher currents or higher inductivity.

Prospects for a high-field, compact break-even axisymmetric mirror (BEAM) and applications

“…The total response time of the feedback system needs to be considerably shorter than the perturbation's growth time and rotation velocity for energy-efficient feedback stabilization. The feedback actuators can take the form of azimuthally segmented and biased end rings (Prater 1971; Kang, Lieberman & Sen 1988; Lieberman & Wong 2002; Be'ery, Seemann & Fisher 2014; Be'ery & Seemann 2015) or magnetic saddle coils on the perimeter of the plasma that can band the static mirror magnetic field (Kogan, Be'ery & Seemann 2016; Beklemishev 2017). A detailed design for a feedback-stabilized plasma with close-fitting conducting shells is underway to be tested on WHAM before being implemented on BEAM.…”