Breakdown and Maintenance of Microwave Discharges in Argon

The breakdown fields for argon have been measured in a resonant cavity at 3000 megacycles/sec. over a pressure range from 3 to 100 mm Hg. The discharge gap approximates the case of a uniform field between parallel plates. The results are compared with predicted values derived from Holstein's theory; the agreement is quite good, about 5 percent. Measurements taken with the discharge in the cavity permit determination of the voltage-current characteristics of the argon microwave discharge. These are given for a set of pressure values. These characteristics are compared with results on positive column gradients in d.c. discharges.