Comparison of Formation Generated and Beam Generated Electron Density Profiles in C-2W

TAE Technologies' C-2U and C-2W devices were designed to form FRC plasmas via collision of accelerated theta pinch compact toroids. [1] Recently, it was announced that developments in neutral beam injection and confinement techniques had allowed for novel formation of these configurations via direct beam injection. [2] Comparison of measurements from the FIR interferometer system [3] of plasmas generated before and after the advent of beam-only generation shows equivalent electron density profiles for both techniques. Since this innovation, subsequent plasmas were freed of initial condition variations and macroscopic instabilities associated with the violent collision-merging process, allowing for successive campaigns of improvement in machine design and plasma control. Examples of plasma shape and behavior as measured by the 14 chord FIR interferometer are presented spanning the original innovation of formation-free plasma start up through the most recent new regime high performance discharges.

[1] H. Gota et al. Overview of C-2W: high temperature, steady-state beam-driven field-reversed

configuration plasmas. Nucl. Fusion 61, 106039 (2021).

[2] T. Roche et al. Generation of field-reversed configurations via neutral beam injection. Nat.

Commun. 16, 3487 (2025).

[3] B. H. Deng, M. Beall, et al. (2016) High sensitivity far infrared laser

diagnostics for the C-2U advanced beam-driven field-reversed configuration plasmas. Review of Scientific Instruments 87:11, 11E125