A hot cathode model: effective work function, lifetime and flicker noise

This paper presents a model of barium migration to the surface and its subsequent removal by evaporation and ion sputtering. We provide estimates on the surface coverage, the effective work function, the current density, and the cathode life. We construct a simple formula that allows a quick assessment of the potential impact on radar systems by the close-to-carrier flicker noise in comparison with the shot noise. Intrinsic noise is an important issue for vacuum electron devices used in present and future radar applications, in particular the gyroklystron amplifier, whose cathode is typically operated at the temperature limited regime (/spl ap/1000/spl deg/C) on which there is little space charge smoothing.