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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2509.08106 |
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| _version_ | 1866911145582919680 |
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| author | Quijada, Martín A. Moya, Pablo S. Navarro, Roberto E. |
| author_facet | Quijada, Martín A. Moya, Pablo S. Navarro, Roberto E. |
| contents | Transverse electromagnetic and electrostatic plasma wave modes propagating along a background magnetic field $\vec{B}_0$ are independent according to linear kinetic theory. However, resonant interactions and energy exchange between waves and particles break this linear decoupling. This work tracks the coupled evolution of Alfvén-cyclotron (ACWs) and Ion-acoustic waves (IAWs) by solving moment-based quasilinear equations for a collisionless plasma of bi-Maxwellian protons and Maxwellian electrons. Unlike earlier quasilinear studies that adopt the cold-electron limit, our formulation retains the full kinetic response of both species, treating the electrons as a thermal reservoir to isolate proton heating. A parameter survey over $0.01\leqβ_{\parallel p}\leq10$ and $1\le T_e/T_p\le10$ shows that an ambient spectrum of ACWs can drive significant perpendicular proton heating and raise the temperature anisotropy from initially isotropic conditions at low $β_{\parallel p}\lesssim0.1$, thereby triggering cyclotron instabilities. The quasilinear evolution self-regulates the ACW, driving the system toward a quasi-stationary state with $γ/Ω_p<10^{-1}$ and reduced anisotropy. As $T_e/T_p$ increases, IAWs become less damped and absorb a larger share of the fluctuation energy through Landau resonance, reducing the efficiency of ACW-driven proton heating and thus regulating the instability. For sufficiently large $β_{\parallel p}$ or $T_e/T_p\gtrsim5$, ACWs become inefficient drivers of perpendicular heating, leaving IAWs as the dominant dissipation channel. These results explain how modest electrostatic activity in low-$β$ environments such as the inner heliosphere and planetary magnetosheaths can regulate, but not indefinitely sustain, cyclotron instabilities. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_08106 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Proton-Acoustic Wave Effects on the Relaxation of Proton Transverse Heating in Magnetized Plasmas Quijada, Martín A. Moya, Pablo S. Navarro, Roberto E. Plasma Physics Transverse electromagnetic and electrostatic plasma wave modes propagating along a background magnetic field $\vec{B}_0$ are independent according to linear kinetic theory. However, resonant interactions and energy exchange between waves and particles break this linear decoupling. This work tracks the coupled evolution of Alfvén-cyclotron (ACWs) and Ion-acoustic waves (IAWs) by solving moment-based quasilinear equations for a collisionless plasma of bi-Maxwellian protons and Maxwellian electrons. Unlike earlier quasilinear studies that adopt the cold-electron limit, our formulation retains the full kinetic response of both species, treating the electrons as a thermal reservoir to isolate proton heating. A parameter survey over $0.01\leqβ_{\parallel p}\leq10$ and $1\le T_e/T_p\le10$ shows that an ambient spectrum of ACWs can drive significant perpendicular proton heating and raise the temperature anisotropy from initially isotropic conditions at low $β_{\parallel p}\lesssim0.1$, thereby triggering cyclotron instabilities. The quasilinear evolution self-regulates the ACW, driving the system toward a quasi-stationary state with $γ/Ω_p<10^{-1}$ and reduced anisotropy. As $T_e/T_p$ increases, IAWs become less damped and absorb a larger share of the fluctuation energy through Landau resonance, reducing the efficiency of ACW-driven proton heating and thus regulating the instability. For sufficiently large $β_{\parallel p}$ or $T_e/T_p\gtrsim5$, ACWs become inefficient drivers of perpendicular heating, leaving IAWs as the dominant dissipation channel. These results explain how modest electrostatic activity in low-$β$ environments such as the inner heliosphere and planetary magnetosheaths can regulate, but not indefinitely sustain, cyclotron instabilities. |
| title | Proton-Acoustic Wave Effects on the Relaxation of Proton Transverse Heating in Magnetized Plasmas |
| topic | Plasma Physics |
| url | https://arxiv.org/abs/2509.08106 |