A diagnostic of gyrotron cathodes quality based on their current-voltage characteristics

In gyrotrons, i.e. sources of powerful (up to 1 MW and higher) coherent microwave radiation the electron beam is formed by a magnetron-injection gun that operates in the regime of temperature limitation set for emission current and with the electric field at the cathode, which is but insignificantly weakened by the field of the spatial charge. Optimization of electron-optical systems in gyrotrons is made more complicated due to strict requirements for homogeneity of helical electron beams and low velocity spread of electrons in the beam. Worse homogeneity of the electron flow leads to a sharp decrease in efficiency or appearance of various instabilities resulting in a break of oscillations. Optimization of parameters of gyrotron guns requires a detailed analysis of many physical processes in the electron-optical system of a gyrotron and application of complex mathematical models.