Oblique electromagnetic electron cyclotron waves for Kappa distribution with AC field in planetary magnetospheres

•Derived dispersion relation for electron cyclotron waves in presence of AC field.•Calculated growth rate of waves in magnetosphere of Jupiter, Saturn and Uranus.•Maximum growth of waves for increasing temperature anisotropy in case of Saturn.•Maximum growth of waves for increasing angle of propagation for Jupiter and Uranus.•Derivation can be modified to study ion cyclotron waves too in magnetospheres.

The dispersion relation for obliquely propagating relativistic electromagnetic electron cyclotron (EMEC) waves in collision-less magnetoplasma is obtained. Investigations for EMEC waves in magnetosphere of Jupiter, Saturn and Uranus have been done, in presence of perpendicular AC electric field for Kappa distribution function. The relativistic temporal growth rate is calculated using method of characteristic solution. Using the data provided by spacecrafts like Cassini, Voyager 1 and 2, while exploring the magnetosphere of Jupiter, Saturn and Uranus, is used to plot graphs showing growth rate being effected by various parameters. Comprehensive parametric analysis have been done at different radial distances of the planets. It is concluded that beside huge difference in magnetospheric configuration, temperature anisotropy remains the main source of energy in case of Jupiter and Uranus. While studying EMEC waves in magnetosphere of Saturn, it is inferred that growth rate attains maximum magnitude when angle of propagation increases. Also, the results and its interpretations explain how the growth of EMEC wave modifies in different magnetospheric conditions.