Noise in planar crossed-field electron guns—II: Numerical solution

Theory and numerical results for the shot effect in an unbounded, parallel-plate, crossed-field diode are presented. The low-frequency régime is studied, where transit-time effects are negligible. It is further assumed that short-circuit conditions prevail, and that the diode is operating in the space-charge-limited régime. Previous theory is first developed into a form suitable for automatic computation. Problems and approaches associated with the numerical solution are then discussed. Finally, results of the computation are presented in normalized form, giving the noise factor for a representative diode as a function of magnetic field. The results show this factor ranging through values less than unity. It follows that, in the present model, feedback effects due to the potential minimum continue to smooth the noise in the presence of magnetic field, just as in the case of no magnetic field.