It has been shown previously  that a crossed-field electron gun consisting of plane-paral1 el cathode and plate gives a space-charge limited current which is independent of cathode length (along the direction in which the beam emerges) over a very wide range. The value of the current may be predicted by the assumption of laminar ( ‘Brillouin*) flow; the emission from the cathode is highly non-uniform. When such guns are used in crossed-field backward wave oscillators, their performance is critically dependent on cathode temperature, being best near temperature limitation, when the emission ismostnearly uniform. A simple extension of the laminar flow result which ensures uniform emission under space charge limited conditions, leads to a theoretical taper for the cathode.-plate space. When such guns are used in backward wave oscillators, their performance is improved, and is no longer critically dependent on cathode temperature once space charge limitation is established. The gun taper derived may be shown to be similar to that obtained by Kino  by somewhat different reasoning.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- Crossed-field electron guns with tapered gaps
B.Sc. A. Reddish
B.Sc. G. Smol
- Macmillan Education UK