Comment on "Langmuir oscillations in a nonextensive electron-positron plasma".

Abstract

Saberian and Esfandyari-Kalejahi [Phys. Rev. E 87, 053112 (2013)10.1103/PhysRevE.87.053112] have discussed Langmuir oscillations in a q-nonextensive electron-positron plasma. However, some of the results obtained and the conclusions drawn in this paper are not appropriate. In Fig.3 of the above mentioned paper, the authors have claimed that for certain values of nonextensivity parameter q the imaginary part of the frequency becomes positive, resulting in unstable oscillations. In this Comment we shall discuss the fact that the Landau damping rate of Langmuir oscillations in a q-nonextensive electron-positron plasma is negative and results in damped oscillations. We hope that this Comment will be helpful in providing a better picture of Langmuir oscillations in nonextensive electron-positron plasma.