Eur. Phys. J. Plus (2022) 137: 182
https://doi.org/10.1140/epjp/s13360-022-02400-8

Regular Article

Fundamental electrostatic modes of PI and NPI plasmas with and without electrons

¹ Theoretical Research Institute, Pakistan Academy of Sciences, 3-Constitution Avenue, G-5/2, 44000, Islamabad, Pakistan
² Department of Physics, School of Natural Sciences (SNS), National University of Science and Technology (NUST), 44000, Islamabad, Pakistan
³ Space and Astrophysics Research Lab. (SARL), National Centre of GIS and Space Applications, 44000, Islamabad, Pakistan
⁴ Department of Space Science, Institute of Space Technology, 44000, Islamabad, Pakistan
⁵ Theoretical Physics Division (TPD), PINSTECH, P. O. Nilore, 45650, Islamabad, Pakistan

Received: 13 September 2021
Accepted: 17 January 2022
Published online: 28 January 2022

Abstract

An analysis of electrostatic ion modes is presented for studying the properties of the negative positive ion (NPI) plasmas produced in Q-machines in USA and the pair ion (PI) plasmas produced in Japan. It is shown that the role of electrons cannot be ignored in the above mentioned NPI plasma even if the ratio of electron density to positive ion density is as small as ${10}^{-4}$ and that this NPI plasma does not meet the criterion for being a pure ionic plasma.The simplified form of this criterion requires ${\omega }_{\mathit{pe}}<<{\omega }_{p\pm }$, where ${\omega }_{\mathit{pe}}={({\mathrm{en}}_{e0}/{ϵ}_0{m}_e)}^{1/2}$ is the electron plasma oscillation frequency and ${\omega }_{p\pm }=({\mathrm{en}}_{+0}/{ϵ}_0{m}_{\pm })$ denotes the ion plasma oscillation frequencies corresponding to singly charged positive and negative ions, respectively. Since ions in PI and NPI plasmas are generally heavier than hydrogen ions, it seems very difficult to achieve this criterion.