An experimental travelling-wave tube equipped with a "Soft-landing" collector

If a collector in a beam-type tube (a TWT for example) captures all the electrons in the spent beam an almost zero velocity, tube efficiency can be greatly improved. Such a collector might be called a "soft-landing" or "depressed" collector. This paper describes the principle, design theory, preliminary experiment, and application of a new type of collector, the TEF (Tilted Electric Field) collector, in which an almost complete soft-landing condition can be realized. In this scheme, several apertured collector plates are tilted with respect to the tube axis so as, to form a tilted decelerating electric field. An axial magnetic field is also applied. In such a structure, the electrons in a multivelocity spent beam are decelerated, velocity-sorted, and collected. The source of the velocity sorting action is the transverse drift motion of electrons provided by the combined action of the axial magnetic field and the transverse component of the electric field.