Measuring particle confinement in C-2W advanced FRCs

A. Cooper, M. Kaur, E. Trask, and the TAE Team

In TAE Technologies’ experimental device, C-2W [1], record-breaking, advanced beam-driven field-reversed configuration (FRC) plasmas are produced. Long-lived, hot FRCs with excluded flux radius up to 50 cm are sustained in a steady-state in the central confinement vessel by utilizing several advanced subsystems. These subsystems include variable energy neutral beams, advanced divertors, end bias electrodes, variable axial magnetic field and mirrors, fueling setup, and an active plasma control system. In this presentation, we will talk about our recent results on improved densities achieved in advanced C-2W FRCs by optimizing the magnetic geometry and mirror strengths. Modifying the magnetic field structure to ionize gas in a low field region near the magnetic axis has increased fueling efficiency which has lead to dense SOL and FRC plasmas. Once the FRC is formed, plasma density is further increased by increasing the mirror strength on both sides of the confinement volume at similar gas fueling, leading to better particle confinement. Higher core density is due to reduced transport to the SOL because of the lower density gradients. Particle confinement time is estimated by using experimentally measured density profiles and calibrated fueling rates.

[1] H. Gota et al., Nucl. Fusion 59, 112009 (2019)