Whistler radiation in plasmas with cylindrical magnetic field irregularities

Abstract

International audienceThe radiation of whistler waves by linear dipole sources immersed in magnetoplasmas with cylindrical magnetic field inhomogeneities are studied. Two types of irregularities are investigated: magnetic field enhancements and depletions. A theoretical analysis is developed for comparatively weak local perturbations of the ambient magnetic field. Results are provided by numerical calculations performed for physical conditions typical of laboratory experiments involving artificially created magnetic field irregularities. It is shown that plasma regions with locally enhanced (depleted) magnetic field intensities can increase (decrease) the amplitudes of whistler waves radiated by dipole sources, regardless of their orientation with respect to the ambient magnetic field. Results are relevant to space and laboratory experiments on very low-frequency wave radiation

Dependence of quasi‐linear diffusion coefficients on wave parameters

“…Theories of VLF power radiation into a magnetized plasma currently lack consensus and verification, despite substantial analysis [ Wang and Bell , 1972; Bell et al , 2006; Song et al , 2007; Krafft and Zaboronkova , 2010], numerical simulation [ Tu et al , 2008; Chevalier et al , 2010], and experimental studies [ James , 2003; Paznukhov et al , 2010; Pribyl et al , 2010]. One notable theoretical expectation is that VLF waves are radiated most effectively at wavelengths comparable to the antenna length.…”