Magnetohydrodynamics

Magnetohydrodynamics has applications to the flow of conducting liquids, and to the motion of laboratory and cosmical plasmas, each in the presence of a magnetic field. The application to thermonuclear devices has already been made the subject of a report by A. A. Ware and is only briefly sketched here. The stress in the present report is on the theoretical aspects.

The discussion of liquid flow is somewhat compressed. It includes, in addition to problems of flow through ducts and around bodies, the theory of various kinds of instability, due to velocity shears, temperature gradients or magnetic stresses. Many examples of the last type of instability also occur in ionized gases.

The discussion of phenomena in ionized gases is preceded by an account of the factors determining electric currents, particularly in a gas at low density. The topics treated include hydromagnetic waves of small and finite amplitudes, the control of thermonuclear devices, and the generation of electricity from fast-moving plasmas.

The final section is concerned with geophysical phenomena arising from the emission by the sun of streams of charged particles. The discussion does not extend down to the ionosphere, in which processes are not genuinely hydromagnetic. It is concerned with the generation of solar streams, with their effects in interplanetary space, and with their interaction with the distant geomagnetic field during magnetic storms.