Large acoustic solitons and double layers in plasmas with two positive ion species
- Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B-9000 Ghent (Belgium)
- School of Physics, University of KwaZulu-Natal, Private Bag X54001, Durban 4000 (South Africa)
- Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)
- Centre for Plasma Physics, Department of Physics and Astronomy, Queen's University Belfast, BT7 1NN, Northern Ireland (United Kingdom)
Large nonlinear acoustic waves are discussed in a plasma made up of cold supersonic and adiabatic subsonic positive ions, in the presence of hot isothermal electrons, with the help of Sagdeev pseudopotential theory. In this model, no solitons are found at the acoustic speed, and no compositional parameter ranges exist where solutions of opposite polarities can coexist. All nonlinear modes are thus super-acoustic, but polarity changes are possible. The upper limits on admissible structure velocities come from different physical arguments, in a strict order when the fractional cool ion density is increased: infinite cold ion compression, warm ion sonic point, positive double layers, negative double layers, and finally, positive double layers again. However, not all ranges exist for all mass and temperature ratios. Whereas the cold and warm ion sonic point limitations are always present over a wide range of mass and temperature ratios, and thus positive polarity solutions can easily be obtained, double layers have a more restricted existence range, specially if polarity changes are sought.
- OSTI ID:
- 21537641
- Journal Information:
- Physics of Plasmas, Vol. 18, Issue 4; Other Information: DOI: 10.1063/1.3579397; (c) 2011 American Institute of Physics; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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