Thomson scattering of a vector Bessel vortex beam by a non-relativistic electron

Abstract

Thomson scattering of a vector Bessel vortex beam (VBVB) by a non-relativistic electron is studied in this paper in order to explore the prospects of vortex beams in Thomson scattering diagnostic in ionospheric or laboratory plasmas. Combining with the plane wave angular spectrum representation of a VBVB, the expressions of scattered electric and magnetic fields are derived with the aid of Thomson scattering theory. The scattered power per unit solid angle and the frequency spectrum of the scattered field in the backscatter direction are simulated numerically, and the effects of polarization, topological charge, half-cone angle, and the electron's motion are analyzed in detail. The results show that the polarization affects the spatial distribution of scattered power. The distance between the electron and the observer's location, where maximum power is received, is affected by the topological charge, and the gaps between sub-maxima are related to the half-cone angle. These characteristics are the manifestation of the retarded effect in radiation. The amplitude spectrum of scattered field is analyzed in which a feature of double peaks is observed. The frequency shifts of peaks are the sum of the shifts brought by the electron's velocity components parallel and perpendicular to the beam's axis. The work provides a significant theoretical foundation for deeply investigating the Thomson scattering of vortex beams by plasmas and is meaningful for the development of plasma diagnostic.