Numerical study of a DRAKON-type closed magnetic configuration with a spatial axis

Abstract

Results are presented from numerical studies of the magnetic field lines and the charged-particle trajectories in the magnetic system of the DRAKON device and of its curvilinear element—the KREL with magnetic mirrors. For the KREL, mirror ratio values are found that do not worsen the particle-drift compensation. The dimensions of the input region for the electrons injected into the KREL to create the beam-plasma discharge are calculated. Calculations show that, in the paraxial approximation, after multiple passes around the device, the magnetic field lines and trajectories of individual transit particles form a system of embedded toroidal surfaces with circular cross sections. When symmetrically changing the current distributions in the coils of the device, these surfaces shift with respect to their previous positions, but their shape remains the same. For the DRAKON device with helical KRELs, the shift of the drift surfaces with respect to the magnetic surfaces, as well as the flow of the longitudinal diamagnetic currents from the KRELs into the rectilinear regions, is found as a function of the pitch angle θ of the KREL helix.