Thermodynamic Theory of Light Ion Beam Propagation in a Plasma

Propagation of a light ion beam in a plasma is investigated theoretically. The basic principle determining the steady state of the beam transport in a plasma is ascertained from the view points of the theory of the irreversible processes. As a preliminary work to discuss the collisional plasma, we consider a state in which the entropy production vanishes and obtain an extended result of Chen and Davidson to include the current due to the drift of the plasma electrons. Two extreme cases are considered: (i) No rotation of the beam around the axis of symmetry or complete neutralization of azimuthal beam current by the plasma electron. (ii) Complete balancing of the electrostatic repulsive force on a beam ion and the magnetically pinching force due to the axial beam current. It is shown that the distribution of ions in a rotational ion beam is given by the Bennett type, provided the current is over-neutralized azimuthally.