Modification of Magnetron Cut-off Characteristics by the Introduction of Positive Ions†

Abstract

Violation of the Hull cut-off criterion is due to cooperative space charge effects within the electron cloud. These cause the appearance of excess energy electrons, and at cut-off a fraction of the anode current consists of elections with abnormally high energy. The cut-off characteristic can be modified by introducing positive ions into the interaction space. These are particularly effective close to the cathode. The experiments suggest that anomalous anode current is due to a slipping stream instability which amplifies small disturbances originating near the cathode.