title: How electron two-stream instability drives cyclic Langmuir collapse and continuous coherent emission.
abstract: Continuous plasma coherent emission is maintained by repetitive Langmuir collapse driven by the nonlinear evolution of a strong electron two-stream instability. The Langmuir waves are modulated by solitary waves in the linear stage and electrostatic whistler waves in the nonlinear stage. Modulational instability leads to Langmuir collapse and electron heating that fills in cavitons. The high pressure is released via excitation of a short-wavelength ion acoustic mode that is damped by electrons and reexcites small-scale Langmuir waves; this process closes a feedback loop that maintains the continuous coherent emission.
authors.affiliation: Department of Astronomy, University of Maryland, College Park, MD 20742; chehh06@gmail.com.|Heliospheric Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771.
authors.forename: Haihong
authors.identifier: 0000-0002-2240-6728
authors.initials: H
authors.lastname: Che
authors.affiliation: Heliospheric Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771.
authors.forename: Melvyn L
authors.initials: ML
authors.lastname: Goldstein
authors.affiliation: Department of Physics, University of California, San Diego, La Jolla, CA 92093.
authors.forename: Patrick H
authors.initials: PH
authors.lastname: Diamond
authors.affiliation: Department of Physics, University of Maryland, College Park, MD 20742.
authors.forename: Roald Z
authors.initials: RZ
authors.lastname: Sagdeev
keywords: Langmuir collapse; coherent emission; electron beams; nonlinear wave interaction; plasma turbulence