Stabilization of global movement on a field-reversed configuration due to fast neutral beam ions

Abstract

Experimental evidence for the global stabilization effect of neutral beam injection on field-reversed configuration (FRC) plasma has been found for the first time. The translation of FRC plasma, i.e., transferring the formed plasma into another vessel along a gradient of guiding magnetic field, is an important technique for both the current FRC experiments and a future fusion reactor to separate formation and confinement regions. However, the translation’s dynamic process causes global wobble movement of the plasma column. The stabilization effect induced by obliquely injected neutral beams on this global movement has been observed by both interferometry and magnetic measurement. The behavior of injected beam ions has been calculated numerically and suggests that the injected beam ions confined under a strong mirror field could produce effective ring-current at both ends of the plasma column. The stabilization effect of this ring-current on the global movement has been discussed by using a rigid body model.

Inductive sustainment of oblate field-reversed configurations with the assistance of magnetic diffusion, shaping, and finite-Larmor radius stabilization

“…The NBI was also observed to assist in the stabilization of FRC global motion. 54 Two other sustainment techniques have received theoretical attention, though without experimental study. Thermoelectric sustainment is based on the observation that more energetic electrons collide less efficiently than cold ones ͑as v r −3 , where v r is the relative velocity͒.…”

MHD Activity in an Extremely High-Beta Compact Toroid

“…The experimental results of the FIX (FRC injection experiment) with neutral beam injection into FRC plasma formed by FRTP, indicate that the global n = 1 mode motion was controlled by neutral beam injection (Asai, et al, 2003). The neutral beam was injected obliquely to the axial direction due to the limited poloidal flux.…”

Losses of neutral beam injected fast ions due to adiabaticity breaking processes in a field-reversed configuration

“…[6][7][8][9][10] The NB injection prolongs up to 240% the e-folding FRC lifetime, 6,7 and a stabilization mechanism induced by NB injection probably reduces the level of global motion; 10 it is a possibility of improvement of confinements. Electron heating is also observed by the Thomson scattering diagnostics.…”