Wave-Energy Partition Governs Weak Collisional Damping in Cold Plasmas
Abstract
Weak dissipation can control wave propagation, mode competition, and instability thresholds in plasmas, yet the physical origin of large branch-to-branch differences in collisional damping is often obscured by dielectric-tensor calculations. We show that weak collisional damping in cold plasmas is governed by wave-energy partition. In the one-rate cold-plasma model, the damping rate of a collisionless eigenmode is exactly the collision frequency multiplied by the fraction of the total wave energy stored in plasma motion. This result recasts the standard perturbative damping formula into a compact and physically transparent law, immediately explaining why field-dominated branches such as whistlers can be much less damped than the collision frequency, whereas quasi-electrostatic modes can exhibit damping of comparable magnitude. Analytic examples for Langmuir, transverse electromagnetic, whistler, and extraordinary waves show that the energy-partition form classifies weak collisional damping across distinct branches and provides a simple diagnostic for mode competition in multibranch plasma-wave systems.
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BibTeX
@misc{zhang2026waveenergy,
title = {{Wave-Energy Partition Governs Weak Collisional Damping in Cold Plasmas}},
author = {Yanzeng Zhang and Xingming Zeng and Xianzhu Tang and Ge Zhuang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.21087},
eprint = {2606.21087},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.21087},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Wave-Energy Partition Governs Weak Collisional Damping in Cold Plasmas
AU - Yanzeng Zhang
AU - Xingming Zeng
AU - Xianzhu Tang
AU - Ge Zhuang
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2606.21087
UR - https://arxiv.org/abs/2606.21087
AB - Weak dissipation can control wave propagation, mode competition, and instability thresholds in plasmas, yet the physical origin of large branch-to-branch differences in collisional damping is often obscured by dielectric-tensor calculations. We show that weak collisional damping in cold plasmas is governed by wave-energy partition. In the one-rate cold-plasma model, the damping rate of a collisionless eigenmode is exactly the collision frequency multiplied by the fraction of the total wave energy stored in plasma motion. This result recasts the standard perturbative damping formula into a compact and physically transparent law, immediately explaining why field-dominated branches such as whistlers can be much less damped than the collision frequency, whereas quasi-electrostatic modes can exhibit damping of comparable magnitude. Analytic examples for Langmuir, transverse electromagnetic, whistler, and extraordinary waves show that the energy-partition form classifies weak collisional damping across distinct branches and provides a simple diagnostic for mode competition in multibranch plasma-wave systems.
ER -