Improvement of beam-tube performance by collector-potential depression, and a novel design

The present state of the art of depressed-collector design is reviewed, and the characteristics of various designs are discussed. A novel design is proposed with desirable characteristics of most present designs but without the common disadvantage of adding to the size and weight of the tube. In the new configuration, the collector is placed off the axis of a magnetic pole piece, whose fringing fields serve to provide, in a simple way, the asymmetry needed to prevent the return of secondary and reflected electrons from the collector region. The performance of the new collector is evaluated experimentally, both in CW and pulsed operation, and is found to be promising. The device is readily adaptable to a rugged, simple collector for a commercial tube. The possibility of modification of the design to include velocity sorting is discussed.