On the Cause of the Anomalous Flicker Effect

Abstract

This paper extends earlier work by Johnson and Donal on the anomalous flicker effect, observed in tubes with a tungsten cathode under space charge limited condition, and attributed to positive ions emitted by the cathode. This extension involves the observation of the individual current pulses causing the effect and the measurement of the flicker effect noise spectrum over a wide frequency range. The results indicate that these pulses are due to sudden bursts of about 104 positive ions emitted by the cathode in less than 1 μsec and trapped in the space charge for many μsec. The trapping time of the ions is determined from the shape of the pulses and from the noise spectrum, and the results are found to agree. An experiment that verifies directly that the effect is caused by positive ions also shows the way to eliminate the effect. A discussion of the nature of these sudden bursts is offered and various mechanisms for the observed decay of the pulses are presented.