Feedback Control of the C-2W Field Reversed Configuration

C-2W is a linear device [1] producing a field-reversed configuration (FRC) toroidal core surrounded by a mirror confined open field line scrape-off-layer (SOL) plasma.

C-2W has demonstrated that it is possible to confine and sustain in steady state an elongated FRC plasma with magnetic feedback control, for as long as the power supplies can maintain it. Large volume FRC plasmas have superior thermal confinement properties but require elongating the plasma to the point where it becomes axially unstable. High frequency, low latency magnetic control is used in C-2W to stabilize the plasma position in real time using radial magnetic fields.

A set of electrodes intersecting with the SOL at both ends of the device are electrically biased at high voltage to stabilize low order global modes. The biassing system is feedback controlled to apply appropriate voltage on electrodes as well as to protect them against over current / arcs.

This work discloses the design and status of the C-2W plasma control system illustrated with recent experimental results.



[1] H. Gota et al., Nucl. Fusion 61, 106039 (2021)