Equilibrium Density Distribution of a Two-Species Plasma with a Single Sign of Charge

Abstract

The equilibrium density distribution of a nonneutral plasma consisting of two species of particles is studied theoretically on a basis of a cold two-fluid model. We request an equilibrium state with rigid rotation and seek the distribution with minimum energy satisfying the conservation of the particle numbers and the canonical angular momentum. The analysis indicates that the overlapping of the distributions of the fluids is allowed only while the total density is below the Brillouin density limit of the heavier fluid. With increasing number of the lighter particles the heavier fluid is pushed out and surrounds the lighter fluid with increasing radial separation. The rotation of the heavier fluid changes from the low frequency branch to the upper branch as the density of lighter particles further increases. When the number of the heavier particles rotating in the low branch is increased, the inner edge of the heavier fluid shrinks to compress the lighter fluid, but when the rotation is switched to the upper branch the outer edge of the lighter fluid expands.