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Description
This work presents the development of a numerical model for simulating Smith–Purcell radiation [1], which arises when a charged particle moves near a periodic grating. The model is implemented in COMSOL Multiphysics [2] and allows for the analysis of the radiation within different frequency ranges, for example, terahertz and gigahertz. It supports variations in grating geometry, observation angles, and particle energy, enabling optimal parametric studies. Near-field and far-field components are calculated to identify main resonances and spectral behavior. Important boundary conditions, for example, Perfect Matched Layer, Impendance Boundary Condition, are used in the model to make it either more optimized or just physically accurate. The model has been validated through comparison with theory. Simulation results for ordinary grating demonstrate the formation of radiation peaks at expected frequencies and angles. This allows further development of the model to be able to simulate more complex geometries such as, i. e., dimer based gratings [3]. Created model provides opportunities for developing compact radiation sources and non-invasive diagnostic devices for charged particle beams.
[1] S. J. Smith and E. M. Purcell, Visible radiation produced by electrons moving in a periodic structure, Phys. Rev. 92, 1069 (1953)
[2] COMSOL Multiphysics, [Online] https://www.comsol.com.
[3] D. Yu. Sergeeva and A. A. Tishchenko, Enhanced Smith-Purcell radiation based on quasibound states in the continuum in dimers aligned in a chain, Phys. Rev. B 108, 155435 (2023).