Author:

Keywords:

Science & Technology, Physical Sciences, Astronomy & Astrophysics, Space plasmas, Solar wind, Shocks, Interplanetary medium, VELOCITY DISTRIBUTIONS, KAPPA-DISTRIBUTIONS, SOLAR, PROTONS, ELECTRONS, UPSTREAM, WAVES, CORE, ISEE-1, C14/19/089#55221731, 0201 Astronomical and Space Sciences, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, 0306 Physical Chemistry (incl. Structural), 5101 Astronomical sciences, 5107 Particle and high energy physics, 5109 Space sciences

Abstract:

In collision-poor plasmas from space, three distinct ion–ion instabilities can be driven by the proton beams streaming along the background magnetic field: left-hand resonant, nonresonant, and right-hand resonant instabilities. These instabilities are in general investigated considering only idealized proton beams with Maxwellian velocity distributions, and ignoring the implications of suprathermal populations, usually reproduced by the Kappa power laws. Moreover, the existing theories minimize the kinetic effects of electrons, assuming them isotropic and Maxwellian distributed. In an attempt to overcome these limitations, in the present paper we present the results of an extended investigation of ion–ion instabilities, which show that their dispersion and stability properties (e.g., growth rates, wave frequencies, and the unstable wavenumbers) are highly sensitive to the influence of suprathermal populations and anisotropic electrons. These results offer valuable explanations for the origin of the enhanced low-frequency fluctuations, frequently observed in space plasmas and associated with proton beams.