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How electron two-stream instability drives cyclic Langmuir collapse and continuous coherent emission
Haihong Che1,2, Melvyn L Goldstein2, Patrick H Diamond3
1Department of Astronomy, University of Maryland, College Park, MD 20742; chehh06@gmail.com.
Summary
Researchers identified a feedback loop maintaining continuous plasma coherent emission through repetitive Langmuir collapse, driven by electron two-stream instability and modulated waves.
Area of Science:
- Plasma Physics
- Nonlinear Dynamics
- Instability Theory
Background:
- Continuous plasma coherent emission requires a sustained energy source and nonlinear processes.
- Electron two-stream instability is a known mechanism for generating plasma waves.
Purpose of the Study:
- To elucidate the underlying feedback mechanism responsible for maintaining continuous plasma coherent emission.
- To investigate the role of Langmuir collapse and wave modulation in plasma emission.
Main Methods:
- Analysis of nonlinear evolution of electron two-stream instability.
- Study of Langmuir wave modulation by solitary and electrostatic whistler waves.
- Investigation of modulational instability leading to Langmuir collapse and electron heating.
- Examination of ion acoustic mode excitation and damping for feedback loop closure.
Main Results:
- Repetitive Langmuir collapse, driven by nonlinear electron two-stream instability, sustains plasma coherent emission.
- Langmuir waves are modulated by solitary waves (linear stage) and electrostatic whistler waves (nonlinear stage).
- Modulational instability results in Langmuir collapse and electron heating within cavitons.
- Release of high pressure via ion acoustic modes, damped by electrons, reexcites Langmuir waves, closing the feedback loop.
Conclusions:
- A detailed feedback loop involving Langmuir collapse, wave modulation, and ion acoustic modes maintains continuous plasma coherent emission.
- The nonlinear interplay between different plasma waves is crucial for sustained coherent emission.
- Understanding this feedback mechanism offers insights into plasma wave generation and energy transfer.
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