Oblique electrostatic ion-cyclotron instability in auroral magnetosphere in the presence of electric field

Abstract

Current-driven oblique electrostatic ion-cyclotron instability in an anisotropic Maxwellian magnetospheric plasma in the presence of perpendicular d.c. electric field has been studied. The dispersion relation has been obtained using the method of characteristics incorporating the details of particle trajectories. The perpendicular electric field provides E_{<img src='http://www.niscair.res.in/jinfo/line.gif' border=0>} x B drift for both electrons and ion, while the parallel electric field gives rise to field aligned drift velocity. The present expression reduced to the well known results under suitable approximations. Growth rate and real frequency have been evaluated for various plasma parameters or auroral magnetosphere having different electron-ion temperature ratios, temperature anisotropics and electric fields. The growth rate is strongly influenced by the field aligned electron drift, ratio of T_{<img src='http://www.niscair.res.in/jinfo/parallel.gif' border=0>e}/T_{<img src='http://www.niscair.res.in/jinfo/line.gif' border=0>i} and anisotropy in electron and ion temperatures. This approach is useful for computer simulation experiments. Various applications of these results have been discussed.