Spherical Plasmoids in Low Pressure Electrodeless Discharges†

‘ Plasmoids ’, of the kind originally observed by R. W. Wood, are luminous plasma bodies occasionally found in low pressure electrodeless discharges. Experiments with spherical plasmoids in. argon at a pressure of 10−4 mm Hg show that the electron temperatures are in the region of 105 to l·5×l05°c and the electron number density is of the order 108 cm−3. Plasmoids are affected by the presence of a probe, and variation in the probe potential can cause large changes in the size of the plasmoid. The plasma equation of Tonks and Laugmuir, for spherical symmetry and for ion generation proportional to the electron density, is solved and an approximate theory is advanced to explain some of the effects observed.