Scattering by a low-velocity charge with applied magnetic fields in a Laguerre–Gaussian beam

Abstract

A method to analyze the scattering characteristics of a Laguerre–Gaussian (LG) vortex beam by a low-velocity charge in a steady applied magnetic field is investigated in this paper. Based on the plane wave angular spectrum representation and the electromagnetic radiation theory of a moving charge, the expressions of the scattered field and scattered power per unit solid angle are presented. Considering a low-velocity electron, the distribution of the scattered power per unit solid angle is numerically simulated. The effects of electron motion parameters, beam parameters, and applied magnetic field are discussed in detail. The results show that the longitudinal motion of the electron, which is parallel to the direction of the applied magnetic field, makes the distribution of the scattered power no longer maintain radial consistency but has a concave–convex distribution. Due to the periodicity of the circular motion of the electron in the applied magnetic field, the scattering power distribution pattern consists of many annular lobes. The spectral characteristics of the backscattered field are analyzed by fast Fourier transform. It is confirmed that the scattered field satisfies the rotational and the linear Doppler effects, and the accuracy of the formula provided in this paper is verified. This work lays a foundation for further study of the scattering characteristics of plasma on vortex electromagnetic waves and helps to promote the in-depth development of vortex beams in the field of plasma diagnosis.

Velocity inversion of a relativistic electron incident by a vortex beam in a magnetic field

“…The interchange between the OAM of vortex beams and plasma waves [10] as well as the effect of non-linear Landau damping on plasma waves with OAM [11] form the theoretical foundation for various applications, such as the fields of vortex beam production [12,13] and plasma modulation [14]. Based on the interaction between electrons and vortex beams [15,16], our team investigated the scattering characteristics of vortex beams by a low-velocity electron [17,18]. However, the relativistic effect cannot be ignored with electrons in hightemperature plasmas and high-phase-velocity electrons.…”