Kappa distributed trapped electrons, drift wave instability and nonlinear structures in O–H plasma of ionosphere

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Generation of drift waves by field-aligned shear flow of protons and oxygen ions is investigated in the presence of kappa distributed trapped electrons in upper ionosphere within auroral latitudes. Very low-frequency electrostatic waves having frequencies of the order of a few Hz observed by Freja satellite at altitude 1700 km can be either the ion acoustic waves (IAWs) or the electrostatic drift waves EDW depending up on density uniformity or non-uniformity in the region. Growth rate of drift wave increases in the presence of 0.4 percent hydrogen ions in oxygen plasma. Drift wave is coupled with the four branches of ion acoustic modes in this bi-ion plasma. In nonlinear regime, EDW and IAWs produce electrostatic solitary structures of a few meters width and their amplitude depends up on the density gradient scale length, non-thermality parameter and trapping of electrons.