High-relativistic effect on ion acoustic soliton in electron–positron–ion plasma

In a high-relativistic electron–positron–ion (epi) plasma, the Korteweg–de Vries (KdV) equation governs ion acoustic waves. This investigation focuses on epi plasma, comprising high-relativistic thermal ions, non-thermal electrons, and thermal positrons, where only rarefactive solitons are shown to exist. Specifically, the fast ion acoustic mode is found to produce tiny amplitude rarefactive KdV solitons. Moreover, the introduction of variable ion species temperatures not only significantly alters the fundamental characteristics (amplitude and width) of ion acoustic solitons (IAS) but also gives rise to a new regime for their existence. In addition, the soliton amplitude decreases as the ion-to-electron temperature ratio rises, while the relativistic factor increases the soliton’s amplitude. These findings have potential applications in both astrophysical plasmas and inertial confinement fusion plasmas.