Liquid conductor model of instabilities in a pinched discharge

The pinched gas discharge experiments seem to have been handicapped by the great speed with which the instability develops as well as by the light coming from impurities instead of the main body of pinched gas. In the present work a liquid conductor is used in order to study the structure of the instabilities. The study of a pinch was made with and without the axial magnetic field. In cases with a magnetic field, the currents and fields were chosen so as to give a longitudinal magnetic field equal to or three times the azimuthal field at the boundary of the mercury stream. The study of the results shows that in the case without an external magnetic field there is a similarity between the behavior of the pinch in a stream of mercury and in an ionized gas column. The stabilizing action of the surface tension is small and the instabilities develop easily. The case with an external magnetic field is more complicated. The magnetic lines of force are not frozen into the medium; they can 'escape' from the medium. In this case the magnetic field has no stabilizing effect. The influence of conducting walls around the mercury column will be studied in forthcoming experiments