Monte Carlo simulation of neutral beam injection into a field reversed configuration

Abstract

A Monte Carlo code is employed to study the interaction of neutral beams with a field reversed configuration (FRC). The code follows the exact particle trajectories in the self-consistent equilibrium calculated including the beam and plasma currents. For high enough beam currents, a self-consistent confining effect is observed which prevents expansion of the beam along the FRC axis. The beam current drive and the power and momentum transferred are calculated for a variety of beam parameters. The results are slightly affected by the details of the injection geometry. The dependence on the neutral current IN and beam energy EN is influenced by several factors, such as particle losses through the ends, the density increase around the injection region and the finite Larmor radius effect.

Equilibrium properties of hybrid field reversed configurations

“…The coalescence of fast ions around the field null (z ¼ 0) seen in earlier 2-D simulations 21 is not observed in Q2D results. This may be explained by differences in neutral beam injection (z ¼ 0.5 m rather than z ¼ 0), beam cross-section (0.1 m radius rather than a pencil beam), beam divergence (1.2 degree half-angle rather than 0 degree).…”

Theoretical analysis of formation and sustainment methods for compact toroids

“…Studies for conditions similar to the best ones achieved in experimental devices [9] show the feasibility of using NBI for current drive in FRC. Fig.…”

Inductive Sustainment of Oblate FRCs with the Assistance of Magnetic Diffusion, Shaping and Finite-Lamor Radius Stabilization

“…This has been proposed in a prominent FRC reactor study, 2 and in the context of driving current at the FRC null 20 during RMF sustainment. A detailed study of tangential neutral beam current drive in a prolate FRC, using a self-consistent equilibrium, was reported in Lifschitz et al 8 For large beam currents, a distortion of the plasma equilibrium leading to a midplane peaking of the beam current density was reported. The beam driven current and its spatial distribution were only weakly modified by the injection impact parameter.…”

“…Historically, most FRCs have been allowed to resistively decay after formation. More recently, techniques have been proposed and/or utilized to sustain the plasma, including neutral beam injection ͑NBI͒ 8,9 and rotating magnetic fields ͑RMF͒ [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] in axially elongated prolate FRCs. For the more spherical oblate FRC, inductive sustainment [27][28][29] has been utilized with some success.…”