Interaction of electromagnetic waves and electron beams in systems with centrifugal-electrostatic focusing

The paper indicates some of the properties of the linear spiratron, a travelling-wave tube with a helical slow-wave structure characterized by centrifugal-electrostatic focusing. The electron beam is tubular, rather than solid, and the slower change of impedance with frequency increases the useful bandwidth and allows comparatively high efficiencies to be maintained down to very low beam currents. The output of this device may be connected to the input to give an electron resonator, and the possibility of forming complex beam shapes by means of the focusing system widens the range of application. It is believed that these electrostatic systems will lead to new methods of generating and amplifying microwaves.