Two-Stream Instability and Bernstein-Greene-Kruskal Mode Formation in Coulomb One Component Plasma
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866915689636298752 |
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| author | Mir, Ajaz Wani, Rauoof Tiwari, Sanat Sen, Abhijit |
| author_facet | Mir, Ajaz Wani, Rauoof Tiwari, Sanat Sen, Abhijit |
| contents | We investigate the Two-Stream Instability in a strongly coupled plasma using classical molecular dynamics simulations with long-range Coulomb interactions between particles. The nonlinear evolution of the instability is identified by the emergence of a Bernstein-Greene-Kruskal (BGK) mode. Our simulations capture key microscopic effects, such as inter-particle correlations, collisional dynamics, and coherent wave-particle interactions-features often absent in traditional fluid and kinetic models, including Particle-In-Cell and Vlasov approaches. In the linear regime, the instability grows rapidly and saturates within a few tens of plasma periods. As the system transitions into the nonlinear saturation phase, a single BGK mode emerges. This mode (or phase-space hole) becomes dynamically unstable in the nonlinear regime, characterized by a continuous decay of electrostatic energy over time. An energy budget analysis reveals a bump in an otherwise thermal spectrum, indicating the excitation of a coherent mode, further confirmed through a numerical rendering of the dispersion relation. The pairwise interaction plays a crucial role: pronounced instability and BGK mode formation occur with long-range Coulomb forces, while such structures are suppressed under shielded Coulomb interactions. We observe the emergence of a single BGK mode across all coupling strengths in the fluid regime, provided the streaming velocity exceeds a critical threshold. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_19281 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Two-Stream Instability and Bernstein-Greene-Kruskal Mode Formation in Coulomb One Component Plasma Mir, Ajaz Wani, Rauoof Tiwari, Sanat Sen, Abhijit Plasma Physics We investigate the Two-Stream Instability in a strongly coupled plasma using classical molecular dynamics simulations with long-range Coulomb interactions between particles. The nonlinear evolution of the instability is identified by the emergence of a Bernstein-Greene-Kruskal (BGK) mode. Our simulations capture key microscopic effects, such as inter-particle correlations, collisional dynamics, and coherent wave-particle interactions-features often absent in traditional fluid and kinetic models, including Particle-In-Cell and Vlasov approaches. In the linear regime, the instability grows rapidly and saturates within a few tens of plasma periods. As the system transitions into the nonlinear saturation phase, a single BGK mode emerges. This mode (or phase-space hole) becomes dynamically unstable in the nonlinear regime, characterized by a continuous decay of electrostatic energy over time. An energy budget analysis reveals a bump in an otherwise thermal spectrum, indicating the excitation of a coherent mode, further confirmed through a numerical rendering of the dispersion relation. The pairwise interaction plays a crucial role: pronounced instability and BGK mode formation occur with long-range Coulomb forces, while such structures are suppressed under shielded Coulomb interactions. We observe the emergence of a single BGK mode across all coupling strengths in the fluid regime, provided the streaming velocity exceeds a critical threshold. |
| title | Two-Stream Instability and Bernstein-Greene-Kruskal Mode Formation in Coulomb One Component Plasma |
| topic | Plasma Physics |
| url | https://arxiv.org/abs/2511.19281 |