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P: Fachverband Plasmaphysik

P 24: Codes and Modeling II

P 24.1: Invited Talk

Thursday, February 29, 2024, 16:30–17:00, ELP 6: HS 4

Electron surface scattering kernel for plasma simulations — •Franz Xaver Bronold and Felix Willert — Institut für Physik, Universität Greifswald, 17489 Greifswald, Germany

Applying the invariant embedding principle, originally developed for the calculation of the albedo of planetary and stellar atmospheres, to secondary electron emission from surfaces, we construct an electron surface scattering kernel to be used in the boundary condition for the electron Boltzmann equation of a simulation of a plasma confined by a solid. In principle, the kernel takes the microphysics responsible for electron emission and backscattering from the plasma-solid interface fully into account. To demonstrate the potential of the approach, we apply it to a polycrystalline silicon surface using a semiempirical jellium-randium model for the solid. It contains the Schottky barrier, impact ionization across the band gap as well as scattering on phonons, defects, and ion cores. The emission yields we deduce from the kernel, which in turn is obtained by solving the nonlinear embedding equation for the electron backscattering function without approximate decoupling of the angle and energy variables, agree well enough with measured data to support using the kernel in the boundary condition of the electron Boltzmann equation of a simulation describing a plasma in contact with a polycrystalline silicon surface. [1] F. X. Bronold and F. Willert, arXiv:2309.00534.

Keywords: secondary electron emission; electron surface scattering kernel; semiclassical transport equation; Boltzmann equation