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<p>The Viking mission identified both cold and hot electron populations in the auroral zone, enabling electron acoustic waves (EAWs) whose nonlinear dissipative interactions are believed to contribute significantly to broadband electrostatic noise (BEN). In this study, we examine the dissipative dynamics of EAWs in collisionless, unmagnetized plasmas using an effective viscosity model. The wave evolution is governed by a Higher Order Boussinesq–Burgers (HOBB) equation that incorporates enhanced nonlinear and dispersive effects. Analytical and numerical investigations reveal that when dissipation dominates over dispersion, the soliton structure transitions into a shock wave. In the weakly dissipative regime, the HOBB equation is solved using the Hirota bilinear method to obtain multi-soliton solutions. A detailed phase-space analysis, Poincaré sections, and near-zero Lyapunov exponents confirm the presence of quasiperiodic behaviour. Energy-based stability criteria show that the solutions remain stable when dissipative effects outweigh dispersive and nonlinear steepening influences. The bipolar electric potential structures predicted by the HOBB equation are analyzed for auroral plasma parameters relevant to Viking observations. The calculated amplitudes and durations of solitary structures show good agreement with measured BEN waveforms. These results demonstrate that the HOBB model successfully captures the interplay of nonlinearity, dispersion, and dissipation, offering a plausible mechanism for the generation of BEN in space plasmas.</p>

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Dissipative electron acoustic solitary, breather and shock structures and nonlinear dynamical analysis in an unmagnetized plasma

  • 期刊论文

  • 发表日期：

    2025年10月8日

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  • Sourav Das,
  • Debjit Dutta,
  • Biswajit Sahu

摘要

The Viking mission identified both cold and hot electron populations in the auroral zone, enabling electron acoustic waves (EAWs) whose nonlinear dissipative interactions are believed to contribute significantly to broadband electrostatic noise (BEN). In this study, we examine the dissipative dynamics of EAWs in collisionless, unmagnetized plasmas using an effective viscosity model. The wave evolution is governed by a Higher Order Boussinesq–Burgers (HOBB) equation that incorporates enhanced nonlinear and dispersive effects. Analytical and numerical investigations reveal that when dissipation dominates over dispersion, the soliton structure transitions into a shock wave. In the weakly dissipative regime, the HOBB equation is solved using the Hirota bilinear method to obtain multi-soliton solutions. A detailed phase-space analysis, Poincaré sections, and near-zero Lyapunov exponents confirm the presence of quasiperiodic behaviour. Energy-based stability criteria show that the solutions remain stable when dissipative effects outweigh dispersive and nonlinear steepening influences. The bipolar electric potential structures predicted by the HOBB equation are analyzed for auroral plasma parameters relevant to Viking observations. The calculated amplitudes and durations of solitary structures show good agreement with measured BEN waveforms. These results demonstrate that the HOBB model successfully captures the interplay of nonlinearity, dispersion, and dissipation, offering a plausible mechanism for the generation of BEN in space plasmas.