Characterisation of electron beams produced by crossed-field secondary emission diodes

The crossed-Field Secondary Emission (CFSE) diode is a compact, simple and cheap source of tubular electron beams in 10¹–10³A range of currents. The physical mechanism of current production is a self-sustained secondary electron emission. The electron beams produced are characterised by extremely high temporal stability and narrow (∼1.4mm) radial current density distributions. A uniform azimuthal current density distribution j(φ) can be achieved by careful adjustment of the cathode-anode assembly. In non-axisymmetric diodes, the j(φ) distributions are strongly non-uniform and depend not only on the magnitude but also on the direction of the magnetic field. Results of the present research show that the CFSE electron sources are ideal candidates for incorporation into medium and high power microwave devices.