Effect of hot injections on electromagnetic ion-cyclotron waves in inner magnetosphere of Saturn

• Published in: Astrophysics and space science 2018-02, Vol.363 (2), p.1-8, Article 33
• Main Authors: Kumari, Jyoti, Kaur, Rajbir, Pandey, R. S.
• Format: Article
• Language: English
• Subjects: Anisotropy; Astrobiology; Astronomy; Astrophysics; Astrophysics and Astroparticles; Cassini mission; Cosmology; Cyclotrons; Density distribution; Equator; Equatorial regions; Field strength; Fluid flow; Ion density (concentration); Latitude; Magnetic fields; Magnetism; Magnetosphere; Observations and Techniques; Original Article; Parametric analysis; Physics; Physics and Astronomy; Planetary magnetic fields; Planetary magnetospheres; Rotational flow; Saturn; Solar system; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Vortices; Wave dispersion; Waves
• ISSN: 0004-640X; 1572-946X
• DOI: 10.1007/s10509-018-3250-0

Encounter of Voyager with Saturn’s environment revealed the presence of electromagnetic ion-cyclotron waves (EMIC) in Saturnian magnetosphere. Cassini provided the evidence of dynamic particle injections in inner magnetosphere of Saturn. Also inner magnetosphere of Saturn has highest rotational flow shear as compared to any other planet in our solar system. Hence during these injections, electrons and ions are transported to regions of stronger magnetic field, thus gaining energy. The dynamics of the inner magnetosphere of Saturn are governed by wave-particle interaction. In present paper we have investigated those EMIC waves pertaining in background plasma which propagates obliquely with respect to the magnetic field of Saturn. Applying kinetic approach, the expression for dispersion relation and growth rate has been derived. Magnetic field model has been used to incorporate magnetic field strength at different latitudes for radial distance of 6.18 R s ( 1 R s = 60 , 268 km ). Various parameters affecting the growth of EMIC waves in cold bi-Maxwellian background and after the hot injections has been studied. Parametric analysis inferred that after hot injections, growth rate of EMIC waves increases till 10 ∘ and decreases eventually with increase in latitude due to ion density distribution in near-equatorial region. Also, growth rate of EMIC waves increases with increasing value of temperature anisotropy and AC frequency, but the growth rate decreases as the angle of propagation with respect to B 0 (Magnetic field at equator) increases. The injection events which assume the Loss-cone distribution of particles, affect the lower wave numbers of the spectra.