Propagation of current and velocity disturbaces in converging electron streams

The method of digital calculation of current and velocity disturbances propagation in converging electron streams are presented. The Poisson equation in 2D axial region is solved by integral equation method. For modeling in time domain algorithm «step by step» is used. Three meshes — one spherical and two rectangular — are used for potential calculation and equation of motion solving. The cathode current is calculated as space charge limited flow. The initial thermal velocities are taken into account. The sinusoidal modulation of current and velocities in cathode start points are introduced. Harmonic analyses is carried out to study the propagation of current and velocity disturbances in gun and drift region with PPM magnetic field. The boundaries of linearity for value of beginning current and velocity disturbances are determined.