Modulational instability of ion-acoustic waves in a plasma with two-temperature kappa-distributed electrons

Abstract

Existence and characteristics of ion-acoustic (IA) wave modulation are studied in a plasma with two-temperature electron satisfying kappa distribution. Based on the multiple time scales perturbation, a nonlinear Schrodinger equation (NLS) is derived. Similar to the case of double Maxwellian electrons, both polarities of envelope soliton can exist over restricted ranges of the fractional hot electron density ratio and two-temperature superthermal electrons. The transition from stable dark solitons to unstable bright ones shifts to the smaller wavelength regions in the presence of cool and hot superthermal electrons. It is shown that the small values of the hot electron populations leads to shrinking the modulation instability region. It is also found the instability growth rate reduces due to the presence of hot electrons. The result of present investigation contributes to the physics of wave modulation in Saturn’s magnetosphere where two-temperature electrons with kappa distribution exist.