Some design problems of foilless diode

Several key problems of foilless diode are discussed. They include (1) the shank-loss, (2) near-cathode area modelling and (3) space charge density calculation. Theoretical results show that the shank-loss cannot be avoided if there exists only the normal component of magnetic field. The planar diode model and the Kino's `short-gun' model are discussed and the Kino's model is indicated to be suitable for the foilless diode. The Weber's model is applied to the calculation of the space charge density.