The paper discusses the potential, space-charge and current density distribution in a “magnetic diode,”i.e., in a linear, smooth anode magnetron. The results of the investigations show that when the initial electronvelocities are taken into account, the electron cloud extends much further into the interelectrode space thancould be expected on the basis of a simple Brillouin flow. Furthermore, the density of the electron clouddecreases monotonically as we move away from the cathode. At the same time, the current flowing parallelto the electrodes has a pronounced peak which is situated half way between the edge of the cloud and thecathode. These results are not only of interest in the steady-state theory of linear magnetrons, but they alsothrow new light on the mode of operation of some thermionic power converters.