Table of Contents
Journal of Astrophysics
Volume 2013 (2013), Article ID 838534, 7 pages
Research Article

Ion-Acoustic Instabilities in a Multi-Ion Plasma

1School of Pure & Applied Physics, Mahatma Gandhi University, Priyadarshini Hills, Kottayam, Kerala 686 560, India
2Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Krishnapuram, Tirunelveli, Tamil Nadu 627 011, India

Received 1 April 2013; Accepted 23 June 2013

Academic Editors: M. S. Dimitrijevic, A. Meli, and S. Naik

Copyright © 2013 Noble P. Abraham et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We have, in this paper, studied the stability of the ion-acoustic wave in a plasma composed of hydrogen, positively and negatively charged oxygen ions, and electrons, which approximates very well the plasma environment around a comet. Modelling each cometary component (, , and ) by a ring distribution, we find that ion-acoustic waves can be generated at frequencies comparable to the hydrogen ion plasma frequency. The dispersion relation has been solved both analytically and numerically. We find that the ratio of the ring speed () to the thermal spread (ts) modifies the dispersion characteristics of the ion-acoustic wave. The contrasting behaviour of the phase velocity of the ion-acoustic wave in the presence of ions for ts (and vice versa) can be used to detect the presence of negatively charged oxygen ions and also their thermalization.