The response of confined plasmas to injection of matter

The dynamics of high temperature, magnetically confined plasma components is described by means of a model incorporating classical friction between ions of the same, as well as different, atomic species. Anomalous diffusion is represented in the general flux expression by a phenomenological, additive term, proportional to the density of the species considered. It is shown that the proper choice of a single, empirical, diffusion coefficient, common to all the species, allows this model to reproduce, at least qualitatively, many of the gross, and some of the finer, features of the density behaviour, already observed, or suspected, in experiments involving injection of matter into plasma vessels: possibility of a steady-state, density and flux profiles, particle life-time, mean-density response time, difference in behaviour of ions of low and high charge numbers, velocity and range of penetration of injected impurity atoms, and rejection of one impurity upon injection of another. Quantitative information is delivered by a numerical code accepting arbitrary temperature, current and magnetic field profiles as input data