Modulational instability of electron-acoustic waves in magnetized plasma in presence of excess superthermal electrons

Modulational instability of finite amplitude electron-acoustic waves along external magnetic field is investigated in plasma composed of inertial cold electrons, hot inertia less superthermal electrons and stationary ions. Reductive perturbation technique is used to derive the three-dimensional nonlinear Schrödinger equation which governs the slow modulation of electron acoustic wave packets. Accounting for effects of hot electron to cold electron number density ratio (α), normalized electron-cyclotron frequency (ω_c ) as well as the electron superthermal parameter (κ_e ) new regimes for modulational instability of electron acoustic waves are obtained and analyzed. The presence of superthermal electrons modifies conditions for modulational instability to occur, as well as associated threshold and growth rate. Concentration of superthermal electrons (i.e., the deviation from a Maxwellian electron distribution) may control or even suppress modulational instability. In contrast to one-dimensional unmagnetized plasmas, instability growth rate is shown to suppress increasing values of k. (author)