The high-power constricted plasma discharge column II. Experimental investigation

Measurements are made of the electrical parameters of high current discharges in capillaries and the results compared with a recent theory put forward by Wheeler in 1970. There is excellent agreement between the experimental electrical characteristic and the theoretical prediction which has the form E α I 2/5 . The capillary voltage drop is found to depend on the nature of the initial gas filling. This is unexpected and leads to a thorough investigation of the process and consequence of wall evaporation. It is shown that the discharge plasma is almost exclusively composed of ionized wall material with an average ionic charge of the order of 3. However, it is suggested that the initial phase of the discharge, which is controlled by the gas filling, influences the subsequent rate of evaporation of wall material.