THREE-DIMENSIONAL SUPERSONIC FLOW COMPUTATIONS

ducting fluid implies the solutions of a coupled electromagnetic field-velocity field problem. Moreover, for very dense plasmas, it is implied that viscosity effects must be included because of their effect on the velocity field near the boundaries of the flow. Nonetheless, it is believed that the magnitudes of each are not significantly different in certain cases. For the example discussed herein, the relatively good agreement between the experimental data and the theory suggests that this is the case. The results of the continuum theory as applied to the experimental situation do not differ in a significant way from the results of the particle approach. An essentially parabolic curve is obtained. This is primarily because of the relative predominance of the initial velocity. This velocity is an experimentally measured value. The experimental arrangement suggests, however, that this measured velocity is more representative of a portion of the ionized fraction of the plasma than of the plasma as a whole. If the velocity of the neutrals were properly weighted (this is assumed in the continuum theory), the initial velocity of the plasma would likely be lower. At higher densities, the continuum equations represent the motion more realistically. The second term in Eq. (8) which takes into account the effects of collisions through such variables as temperature and pressure will exercise greater importance as the density increases, and hence the departure from the parabolic dependence of exit velocity on field maximum would become more pronounced. Lower initial velocities would also cause a departure from the parabolic curve.