Radial Hydromagnetic Oscillations

This paper discusses the radial hydromagnetic oscillations of a plasma confined by an axial magnetic field. Oscillations of this type have recently been observed experimentally in this laboratory and typical high speed streak photographs are presented and analysed. On the assumption that the plasma is confined in a thin cylindrical annulus, the non-linear equation of motion can be integrated analytically. The calculated period of the oscillations is independent of amplitude and is found to be in good agreement with experimental results. Damping of the oscillations by diffusion of the magnetic field is discussed and reference made to the possible significance of the oscillations as a means of transferring energy irreversibly to the ions.