# Effect of thermal ions on fluid nonlinear frequency shift of ion acoustic waves in multi-ion species plasmas

## TL;DR

This paper develops a comprehensive fluid model for ion acoustic waves in multi-ion plasmas, incorporating ion temperature effects to improve the accuracy of nonlinear frequency shift predictions relevant to space physics and fusion.

## Contribution

It introduces a new model that accounts for thermal ions and multiple ion species, extending previous cold ion models for better accuracy in nonlinear frequency shift calculations.

## Key findings

- The model predicts more accurate frequencies for large amplitude IAWs.
- Thermal ion effects significantly influence the slow mode in multi-ion plasmas.
- Applicable to space physics and inertial confinement fusion scenarios.

## Abstract

A model of the fluid nonlinear frequency shift of ion acoustic waves (IAWs) in multi-ion species plasmas is presented, which considers the effect of ion temperature. Because the thermal ion exists in plasmas in inertial confinement fusion (ICF) and also solar wind, which should be considered in nonlinear frequency shift of IAWs. However, the existing models [Berger et al., Physics of Plasmas 20, 032107 (2013); Q. S. Feng et al., Phys. Rev. E 94, 023205 (2016)] just consider the cold ion fluid models. This complete theory considering multi-ion species and thermal ions will calculate the frequency of the large amplitude nonlinear IAWs more accurately, especially the slow mode with high ion temperature, which will have wide application in space physics and inertial confinement fusion.