A pulsed corona-Townsend method for measurement of electron/ion number ratios and drift velocities

A new, easily-implemented method based on the pulsed-Townsend technique has been developed to measure drift velocities of charge carriers in a corona discharge at atmospheric pressure. The method also yields the electron/ion number ratio and an upper limit on the value of the electron attachment coefficient. Approximate electron drift velocities measured in nitrogen are in agreement with known values. In addition, the negative ion mobility obtained in nitrogen containing small amounts (0-3.7%) of oxygen agrees with known data. Therefore the pulsed corona-Townsend technique can be used to obtain data in gas mixtures of practical interest. The method can also distinguish the charge carriers in a corona discharge. This is especially useful in nonelectronegative gases with unknown concentrations of electronegative impurities.<>