Cathode comprising a substrate (2) supporting a cathode emissive coating, comprising what is called an emissive central zone (12) and what is called a nonemissive peripheral zone (11); according to the invention: the average density and the emissive zone (12) is greater than that in said nonemissive zone (11), the average thickness in the emissive zone (12) is less than that in the nonemissive zone (11). In this way it is possible to significantly limit the drift in cut-off voltage, while still maintaining good maximum emission performance in DC mode and in pulse mode.