Effects of Ion Collisions on Quasilinear Heating by the Current-Driven Ion Cyclotron Instability in the High Latitude Ionosphere PDF Download

Author: P. Satyanarayana
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Languages : en
Pages : 25

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Book Description
Using an effective relaxation time model, the effects of ion-ion and ion-neutral collisions on quasilinear ion heating by the current-driven ion cyclotron instability in the high latitude ionosphere have been studied. For conditions typical of the high latitude lower (200-300 km) F-region ionosphere, it is found that the combined effects of ion-neutral and ion-ion collisions tend to isotropize (S(tet)/T(par) approx. 1) the perpendicular T(per) and parallel S(tet) ion temperatures on time scales on the order of several tens to hundreds of NO+ cyclotron periods for wave amplitudes e(phi)/T sub e = 0.2. Here, phi is the wave electrostatic potential, T(par) the electron temperature (in energy units), e is the electron charge. In addition, for the high latitude upper (600 km) F-region ionosphere it is found that stronger anisotropy (T(per)/T(par)> 3) can be sustained even in the presence of ion collisions with waves with amplitudes e(phi)/T sub e = 0.2. For larger amplitude waves e(phi)/T sub e = 0.4, we find that the heating is weakly anisotropic at low altitudes (200-300 km) and strongly anisotropic at higher (600 km) altitudes. In both wave amplitude regimes (0.2 and 0.4), we find perpendicular ion heating factors about 2-10 for altitudes in the range 300-600km, with the larger perpendicular heating occurring at higher altitudes and larger wave amplitudes. The results are compared with recent rocket and satellite observations in the high latitude ionosphere. Keywords: Ion cyclotron instability; Ion heating. (jhd).