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Abstract

A fast Z-Pinch in 1.22 Torr helium has been investigated electrically, photographically, and spectroscopically in order to determine the important parameters of the discharge. The dI/dt oscillogram has been used in conjunction with the circuit equations to find the current shell radius and velocity as functions of time. The dynamics have been modelled numerically using a modified snowplow model. The luminous zone of the plasma has been photographed end-on using a TRW image convertor camera. The radial distribution of the plasma measured on the end-on photographs is found to agree with both the electrical determination of the current shell radius and the radius given by the model. The time-resolved electron temperature and electron density were measured spectroscopically using the He II 4686 Å emission line. The measurements show that the plasma has parameters of 10 eV and 10¹⁸ cm⁻³ just before pinching and 37 eV and 8x10¹⁸ cm⁻³ during the 400 ns pinch phase. The results show that the plasma is well suited to the requirements of the future light mixing experiments.