a1 Max-Planck-Institut für Aeronomie, Katlenburg-Lindau, Germany
a2 Physical Research Laboratory, Ahmedabad, 380009 India
In this paper it is shown that a stationary plasma can be accelerated by a moving neutral gas only if the velocity of the neutral gas exceeds Alfvén's critical velocity. An expression for the terminal velocity of the interaction is given which shows that, in the limit of high incoming neutral gas speeds, the composite plasma is accelerated up to one quarter of the gas speed. We also discuss terminal velocities associated with the inverse problem, namely the deceleration of a magnetized plasma as a result of its motion through, and interaction with, a stationary neutral gas.
(Received October 06 1979)
(Revised October 22 1980)
† Present address: Department of Mathematics and Applied Mathematics. University of Natal, South Africa.