The effect of an applied static electric field on trapped beam electrons in a traveling wave tube has been observed. In particular, it was found that the wave power can be increased. It was found that beam space charge can play an important role in limiting the wave-power enhancement, and that the wave enhancement is strongly dependent on the rf input drive level. By launching large-amplitude waves over 10 dB of enhanced wave growth has been observed.

• Received 3 May 1982

DOI:https://doi.org/10.1103/PhysRevLett.49.546