Measurement of transport properties of SF₆ at high temperatures and pressures

The electrical and thermal conductivity and the net radiation emission of a sulfur hexafluoride plasma were measured for temperatures up to 22 500 K at 1, 4 and 8 bar. These measurements were made on wall stabilized cascade arcs of 3 and 5 mm diameter using spectroscopy. The electrical conductivity was in fair agreement with the theory but was found to be pressure dependent. The thermal conductivity k, at 1 bar pressure was in good agreement with the other experimental results of Frie and Motschmann, but was higher by a factor of three as compared to the theoretical estimates of Frost and Liebermann. At 4 and 8 bar the values of k were higher by a factor of six and eight, respectively. The high value of the thermal conductivity was attributed to the contribution of the thick radiation absorption within the arc column. These experimental measurements have shown for the first time, the strong pressure dependence of the apparent thermal conductivity. The net radiation emission u was also found to be higher, by up to a factor of two, as compared to the theoretical estimates of Liebermann and Lowke.