First Demonstration of the Simplest Cross-field Ubitron

The simplest cross-field ubitron is a magnetically insulated coaxial diode with a cold cathode comprising a number of longitudinally oriented single emitters periodically arranged in the azimuthal plane of the diode (a "transparent cathode"). This type of cathode is essentially a wiggler with azimuthally periodic magnetic and electric fields exciting radially oscillating electron currents within the electron flow rotating around the cathode in crossed magnetic and electric fields. The cathode inside the waveguide is also a periodic electro-dynamical system characterized by a set of azimuthal eigenmodes capable of synchronously interacting with the excited radially oscillating currents. Computer simulations of the cross-field ubitron demonstrate controlling microwave generation by changing the external magnetic field with efficiency of >10%. Results of initial experiments are presented