On the structure of the boundary layer in a Beklemishev diamagnetic bubble

Abstract

The article provides a kinetic description of the plasma equilibrium in the Beklemishev diamagnetic trap, where the traditional approach based on the theory of magnetic drifts is not applicable, since the ions move in a substantially non-circular orbit, the diameter of which is approximately equal to the diameter of the diamagnetic bubble. The ion distribution function was found in the collisionless approximation, neglecting the diamagnetic electron current. The radial profile of the magnetic field, the plasma density, the current density, and the components of the pressure tensor are calculated. It was found that the width of the boundary layer in the diamagnetic bubble varies from 6 to 8 Larmor radii calculated by the vacuum magnetic field. An adiabatic invariant is calculated that replaces the magnetic moment, which is not conserved in the diamagnetic bubble. The criterion of absolute confinement is formulated and the plasma equilibrium is found for the case when the adiabatic invariant is not conserved and only ions whose velocity satisfies the criterion of absolute confinement are trapped.