Whistler Mode Wave Refractive Index in a Finite Temperature Anisotropic Plasma Medium
Keywords:
oblique whistler waves, radiation belts, raytracing, warm plasma, whistler modeAbstract
Whistler mode waves, which exist in a magnetized plasma, are prevalent in the Earth's magnetosphere in the extremely low frequency (ELF) and very low frequency (VLF) bands (100 Hz - 30 kHz). Due to the impact of whistler mode waves on space weather processes, it is important to accurately predict the propagation trajectory of these waves and their properties. Numerical raytracing determines the power flow path of the whistler mode waves in the anisotropic medium of the magnetosphere based on local calculation of the refractive index. In the majority of previous work, magnetospheric raytracing has been implemented assuming a cold background plasma (0 K). However, a more accurate description of the magnetospheric plasma includes a background temperature of about 1 eV (11600 K). We present solutions to the dispersion relation that include the effects of finite electron and ion temperatures on the wave refractive index using a warm plasma formulation. Finite temperature effects of the background plasma are shown to be most significant for highly oblique wave normal angles where the refractive index is bounded to smaller values than in the ideal cold plasma approximation.
Downloads
References
U. S. Inan, S. Umran, and M. Gołkowski, Principles of Plasma Physics for Engineers and Scientists. Cambridge University Press, 2010.
P. M. E Decreau, C. Beghin, and M. Parret, “Global characteristics f the cold plasma in the equatorial plasmasphere region as deduced from the GEOS 1 mutial impedance probe,” J. Geophys. Res A87, 695, 1982.
J. Haselgrove, “Ray theory and a new method for ray tracing,” in Physics of the Ionosphere, Physics of the Ionosphere Conference, Cambridge, London, 355-364, 1954.
P. Kulkarni, M. Gołkowski, U. S. Inan, and T. F. Bell, “The effect of electron and ion temperature on the refractive index surface of 1-10 kHz whistler mode waves in the inner magnetosphere,” J. Geophys. Res. Space Physics, 120, 1, 581-591, 2015.
A. S. Maxworth and M. Gołkowski, “Magnetospheric whistler mode raytracing in a warm background plasma with finite electron and ion temperature,” J. Geophys. Res. Space Physics, 122, 7, 7323-7335, 2017.
Q. Ma, et al., “Very oblique whistler mode propagation in the radiation belts: Effects of hot plasma and Landau damping,” Geophys. Res. Lett., 2017.
D. M Malaspina, et al., “The distribution of plasmaspheric hiss wave power with respect to plasmapause location,” Geophys. Res. Lett., 43, 15, 7878-7886, 2016.
R. B. Horne and S. S. Sazhin, “Quasielectrostatic and electrostatic approximations for whistler mode waves in the magnetospheric plasma,” Planetary and Space Science, vol. 38, iss. 2, 1990.
R. B. Horne “Path‐integrated growth of electrostatic waves: The generation of terrestrial myriametric radiation,” J. Geophys. Res., 94, A7, 8895-8909, 1989.
J. M. Albert, “Quasi-linear diffusion coefficients for highly oblique whistler mode wave,” J. Geophys. Res., 122, 5, 5339-5354, 2017.
