Abstract
AbstractWe have conducted a one‐dimensional electromagnetic particle simulation with a parabolic magnetic field to reproduce whistler‐mode hiss emissions in the plasmasphere. We assume a bi‐Maxwellian distribution with temperature anisotropy for energetic electrons injected into the plasmasphere and find that hiss emissions are generated with spectrum characteristics typical of those observed by spacecraft near the magnetic equator. The hiss emissions contain fine structures involving rising tone and falling tone elements with variation in frequencies. The amplitude profile of the spectra agrees with the optimum wave amplitude derived from the nonlinear wave growth theory. The simulation demonstrates that hiss emissions are generated locally near the magnetic equator through linear and nonlinear interactions with energetic electrons with temperature anisotropy. The coherent hiss emissions efficiently scatter resonant electrons of 2.5–80 keV into the loss cone.
Highlights
Whistler‐mode hiss is a commonly occurring electromagnetic emission in the Earth's plasmasphere and plasmaspheric plumes
We have performed a self‐consistent electromagnetic full particle simulation around the magnetic equator with a dipole field which is approximated by a parabolic function
In order to reproduce plasmaspheric hiss emissions, we set up anisotropic energetic electrons that resonate with whistler‐mode waves assuming plasmaspheric parameters
Summary
Whistler‐mode hiss is a commonly occurring electromagnetic emission in the Earth's plasmasphere and plasmaspheric plumes. Dependent on local magnetic conditions, typical hiss frequencies range from ∼100 Hz to several kHz, and amplitudes range from a few pT to hundreds of pT. Dependent on the location of the plasmapause and plasmaspheric plumes, hiss can efficiently pitch‐angle scatter electrons in the energy range from. Hiss is a primary agent for influencing the distribution and dynamics of electrons throughout the inner magnetosphere (e.g., Breneman et al, 2015; Li et al, 2014; Meredith et al, 2006; Ni et al, 2014; Summers et al., 2007a, 2007b; Thorne et al, 2013; Tsurutani et al, 1975; Zhang et al, 2018). Cyclotron resonant pitch‐angle scattering by plasmaspheric hiss is considered responsible for the formation of the “slot region”
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