Numerical simulation of the operation of a wide-aperture electron gun with a grid plasma emitter and beam output into the atmosphere

Numerical simulation of physical processes in the electron-optical system of the DUET accelerator was carried out using the ERA-DD code. Calculations were carried out on adaptive quasi-structured grids developed by the authors. A mathematical model for the emission plasma surface deformable when solving the problem is proposed. In this model, the problem is considered in a two-dimensional axisymmetric approximation and the front of the electron entrance to the computational domain is represented as a set of circular arcs connected by necks. In order to increase the accuracy of the calculations, it is proposed to split the multi-scale extended domain into two subdomains and alternately solve self-consistent problems in the subdomains using the alternating Schwartz method. The beams are simulated by the method of current tubes, and the electric field potential is calculated by the finite volume method. The obtained characteristics of the beam are compared with experimental data. It is shown that for the operating parameters of the beam source, its losses on the accelerator elements are minimal and are primarily due to the imperfect alignment of the holes in the mask and the reference grid, as well as to deviations of electron beams generated by structures localized on the periphery of the emission electrode.