https://doi.org/10.1140/epjp/s13360-025-06074-w
Regular Article
A comparative study of the nonrelativistic and ultrarelativistic linear dispersion relations of electromagnetic waves in anisotropic classical plasmas: an alternative approach
1
Department of Physics, Government College University, 54000, Lahore, Pakistan
2
Department of Physics, Forman Christian College University, 546000, Lahore, Pakistan
3
Salam Chair in Physics, Department of Physics, Government College University, 54000, Lahore, Pakistan
4
Department of Physics, Government Gulberg College, 54000, Gulberg, Lahore, Pakistan
a
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Received:
20
August
2024
Accepted:
2
February
2025
Published online:
19
March
2025
Abstract
An alternative form of the dielectric tensor, for evaluating unmagnetized response functions in thermally anisotropic collisionless plasma, is considered. The approach incorporates anisotropy in the momentum space, characterized by the modified momentum magnitude. Previously applied to Fermi distributed systems, this momentum space anisotropy concept is extended to classical systems. The method involves adjusting an isotropic distribution function along one direction in the momentum space. The equilibrium bi-Maxwellian distribution function is presented, parameterized by the anisotropy parameter 
and the pitch angle 
. Our results align with standard nonrelativistic outcomes. For ultrarelativistic classical systems, our findings, except for Landau damping and the hydrodynamic growth rate, coincide with the standard nonrelativistic case. The formulation offers a fresh perspective on the unmagnetized response functions in collisionless plasma by considering thermal anisotropy in classical systems. The extension of momentum space anisotropy to such systems provides a valuable framework for understanding plasma behavior, with potential applications in diverse physical scenarios.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
