Pulsed-field mobilities of the charge carriers in ionized gases

Mobilities of the carriers of charge were determined in high purity media at a pressure slightly above the atmospheric and temperatures from 20 to 80 centigrade. It has been determined that mobility values depend on the purity of the medium; the media of P.A. class of purity were used. The medium was confined in a small cylindrical polytetrafluoroethylene chamber (10 mm dia, 10 mm length). The two end electrodes were circular, identical in size (10 mm dia), one of them acting as anode, the other as cathode. The anode was made of stainless steel coated with a layer of deposited gold, the cathode was at titanium with a layer of tritium adsorbed on its surface. The operating cycle of the chamber consisted of the prevailing quiescent state, when the electrodes were grounded, and of the active state, during which an axial electric field was applied to the chamber. The field was created by biasing the cathode briefly with a short negative pulse, while the anode was kept at ground potential. The medium, in which the mobility was measured, was flown slowly, axially, through the chamber (10 ml.min/sup -1/), entering via the anode. The tritium low energy beta radiation, created a localized layer of electrically neutral plasma near the cathode whose axial dimension was approximately four millimeters during the quiescent equilibrium state. During the active state, when the electric field was applied, the charge was separated in the plasma layer. Electrons, possessing greater mobility, were first to be collected by the anode; subsequently, the positive ions were gathered. The field amplitude-time dependence, that reflected the charge separation and collection was correlated with the electric current waveform; these parameters were used for the determination of the electron mobilities. The mobility data were measured in ultra-high purity argon and in binary mixtures of argon with other gases. The mobility data obtained in the course of this study are of value in the determinatio- of the voltage-current dependencies and other characteristics of corona discharges. The data are of special interest to those, who study the physical phenomena in pulsed and steady state corona discharges, or are interested in the design of detectors for gas analysis.