Beam effect on electromagnetic ion-cyclotron waves with general loss - cone distribution function in an anisotropic plasma-particle aspect analysis

• Published in: Annales geophysicae (1988) Vol. 25; no. 2; pp. 557 - 568
• Main Authors: AHIRWAR, G, VARMA, P, TIWARI, M. S
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau European Geophysical Society 01.01.2007; European Geosciences Union; Copernicus Publications
• Subjects: Earth Sciences; Earth, ocean, space; Exact sciences and technology; External geophysics; Ocean, Atmosphere; Physics of the high neutral atmosphere; Physics of the ionosphere; Physics of the magnetosphere; Sciences of the Universe; Plasma physics; Ion cyclotron wave; Space plasma physics (Waves and instabilities); Dispersion relation; Ion beam; Velocity distribution; Ion distribution; Thermal anisotropy; electromagnetic waves; Ion temperature; Charged particle; Distribution function; Magnetoactive plasma; Electromagnetic instability; growth rates; Magnetospheric physics (Auroral phenomena); Homogeneous plasma; Ionosphere (Wave-particle interactions); Electrostatic wave; trajectory; Loss cone; Wave emission; free energy; Anisotropic plasma; Particle wave interaction
• ISSN: 0992-7689; 1432-0576; 1432-0576
• DOI: 10.5194/angeo-25-557-2007

The effect of upgoing ion beam and temperature anisotropy on the dispersion relation, growth rate, parallel and perpendicular resonant energies, and marginal instability of the electromagnetic ion cyclotron (EMIC) waves, with general loss-cone distribution function, in a low β homogeneous plasma, is discussed by investigating the trajectories of the charged particles. The whole plasma is considered to consist of resonant and non-resonant particles. The resonant particles participate in an energy exchange with the waves, whereas the non-resonant particles support the oscillatory motion of the waves. The effects of the steepness of the loss-cone distribution, ion beam velocity, with thermal anisotropy on resonant energy transferred, and the growth rate of the EMIC waves are discussed. It is found that the effect of the upgoing ion beam is to reduce the energy of transversely heated ions, whereas the thermal anisotropy acts as a source of free energy for the EMIC waves and enhances the growth rate. It is found that the EMIC wave emissions occur by extracting energy of perpendicularly heated ions in the presence of an upflowing ion beam and a steep loss-cone distribution function in the anisotropic magnetoplasma. The effect of the steepness of the loss-cone is also to enhance the growth rate of the EMIC waves. The results are interpreted for EMIC emissions in the auroral acceleration region.