Bharuthram, Ramesh.Pillay, Sadhasivan Rangan.Lazarus, Ian Joseph.2013-01-142013-01-1420092009http://hdl.handle.net/10413/8297Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2009.The behaviour of both small amplitude and arbitrary amplitude nonlinear electrostatic fluctuations are studied in electron-positron plasmas. The propagation characteristics of associated linear modes are also examined for selected plasma models. In the case of the four component, two-temperature, electron-positron plasma, three particular features are investigated. The first investigates existence conditions of the range of possible electrostatic linear waves that can propagate in a two-temperature electron-positron plasma, the study being particularly relevant to both astrophysical situations and laser induced fusion experiments. The second includes the development and investigation of the mKdV-ZK equation governing the three dimensional propagation of solitary waves in a magnetized plasma. The third application is the investigation of nonlinear electrostatic solitary waves structures, similar to those found in the broadband electrostatic noise observed in various regions of the earth’s magnetosphere. The study ends by considering relativistic effects on solitary waves in an electron-positron plasma.en-ZAPlasma (Ionized gases).Theses--Physics.Thesis