On the Scattering of Electromagnetic Waves by a Charged Sphere

Abstract

Abstract-Scattering of electromagnetic radiation by a charged homogeneous spherical particle/body is treated. Theoretical solution represents a generalization of the Mie's scattering theory for electrically neutral sphere. It is shown that classical and quantum physics approaches may lead to different conclusions, as documented by numerical computations assuming various permeabilities, refractive indices, surface charges, temperatures, and other physical parameters of the spherical particles. Two discrete wavelengths (5 µm and 1 mm) of the incident radiation are considered. Optical properties of charged particles composed of absorbing and slightly absorbing materials can essentially differ. Especially, the resonance peaks typically occur when imaginary part of particle refractive index is low. The relative permeability of a material may differ from unity at large wavelengths, e.g., in microwave region. Basically, the relative permeability appears to be less important factor than the surface charge. However, the permeability can influence the scattering and extinction efficiencies, as well as the backscattering features of small particles, under some conditions.

The electric field in sandstorm can strongly affect the sand׳s scattering properties

“…Here, ε 0 is the permittivity of environmental medium, E h is the intensity of the environmental electric field at the location of sand, and H ðθ À θ 0 Þ is the Heaviside function [14]. In this paper we employed a spherical polar coordinate system with coordinates ðr; θ; φÞ and a rectangular coordinate system with coordinates ðx; y; zÞ; the corresponding unit base vectors are ðr; θ; φÞ and ðx; y; zÞ, respectively.…”

“…Some theoretical models and various numerical techniques have been found to predict the optical properties of particles [3,4], but most of them have neglected the effects of the environment factors, except for the environmental humidity [5] and the adhesion of mineral and soot aerosols [6,7]. However, most particles of interest in astrophysics and atmospheric sciences are charged [8][9][10][11][12], and those electrified particles not only enhance the attenuation of incident EM wave [13][14][15][16][17][18][19][20], but also generate a strong Electrostatic field (signed as E-field for short). For example, the charged sands or dusts can produce a strong E-field in the air [21][22][23][24][25][26], and the maximal intensity can reach up to 200 kV/m [27,28].…”

Effect of charges carried by atmospheric particles on radar power ratio

“…is the surface conductivity analogous to the (bulk) conductivity and it may be complex and depend on the frequency. Bohren and Hunt (Bohren and Hunt, 2011) and Klačka et al (Klačka and Kocifaj, 2007;Klačka. and Kocifaj, 2010) studied , usually expressed as = + .…”

“…Bohren et al theoretically studied the scattering of EM waves by a charged particle and found that the scattering coefficients of particles carrying 10 charges and neutral particles greatly differ (Bohren and Hunt, 2011). Klačka's research group later conducted a series of studies to investigate the scattering/absorption of dust particles, water droplets, and ice grains, finding that charges carried by the particles affect the optical properties of the particles and the scattering/absorption of EM waves when the particle size parameter (2 / , in which r is the particle radius and λ is the EM wavelength) is less than 0.01 (Klačka and Kocifaj, 2007;Klačka. and Kocifaj, 2010;Klačka et al, 2015).…”

Scattering of Gaussian Beam by a Spheroidal Particle

“…The generalized Lorenz-Mie theory (GLMT) developed by Gouesbet et al is effective for describing the interaction of a shaped beam with a spherical particle by relying on the separability of variables [1][2][3], and has been extended by so many researchers to multilayered spheres [4,5], spheroids [6] and infinite cylinders [7][8][9]. Various applications of focused beam scattering include optimizing the rate at which morphology-dependent resonances (MDRs) are excited, laser trapping, particle manipulation, and the analysis of optical particle sizing instruments [10,11].…”