Upper hybrid solitons and oscillating-two-steam instabilities

Abstract

A warm two-fluid theory of soliton formation near the upper-hybrid frequency is developed. Several forms of the nonlinear Schroedinger equation are obtained, depending on whether the electric field is completely perpendicular to the dc magnetic field or whether it has an additional small component parallel to the magnetic field. For the perpendicular case, the character of the soliton depends on its scale length, L, and on $beta$. For low $beta$, when L is less than c/$omega$/sub pe/, one finds stationary envelope and hole solitons, whereas when L is greater than c/$omega$/sub pi/ we obtain the super-Alfvenic solitons described by Kaufman and Stenflow by MHD theory. However, the case E/sub parallel/ not equal to 0 may be of more interest, since it couples the pump to the excited waves more efficiently. In the limit of linearization about an infinite wavelength pump, the nonlinear Schroedinger equations yield purely growing (oscillating-two-stream) instabilities in both cases. (auth)