New light on ion acoustic solitary waves in a plasma with two-temperature electrons

¹ School of Physics, University of KwaZulu-Natal - Private Bag X54001, Durban 4000, South Africa
² Mbarara University of Science and Technology - P. O. Box 1410, Mbarara, Uganda
³ Sterrenkundig Observatorium, Universiteit Gent - Krijgslaan 281, 9000 Gent, Belgium, EU

^a balukuthomas@yahoo.co.uk

Received: 27 April 2010
Accepted: 23 June 2010

Abstract

Ion acoustic solitary waves in two-temperature electron plasmas have been studied in the past, and negative-potential solitons and double layers found, in addition to positive-potential solitons. Here, further investigations show that positive-potential double layers can form below a critical density ratio, associated with the third derivative of the Sagdeev potential evaluated at the origin for the phase velocity of the linear wave. For density ratios that support positive double layers, solitons are also reported beyond the double layers, depending on the cool-to-hot electron temperature ratio. In addition, when both polarities can be supported, solitary structures can propagate at the acoustic speed, contrary to a KdV prescription.