Incoherent Scattering of Electromagnetic Waves by Langmuir Fluctuations Trapped in a Plasma Density Well

• Published in: Plasma physics reports Vol. 44; no. 9; pp. 805 - 819
• Main Author: Puchkov, V. A.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-09-2018; Springer Nature B.V
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Atomic; DISTRIBUTION FUNCTIONS; ELECTROMAGNETIC RADIATION; ELECTRON COLLISIONS; ELECTRON DENSITY; FLUCTUATIONS; INCOHERENT SCATTERING; Langmuir waves; Mathematical analysis; Molecular; Optical and Plasma Physics; Oscillations; Oscillations and Waves in Plasma; Physics; Physics and Astronomy; Plasma; PLASMA DENSITY; Quasi-Periodic Oscillations; Variation; Velocity distribution
• ISSN: 1063-780X; 1562-6938
• DOI: 10.1134/S1063780X18090106

Incoherent scattering of a probing wave by Langmuir fluctuations trapped and enhanced near a local minimum of the electron density (plasma density well) in plasma with a parabolic density profile is considered. Steady-state amplitudes of fluctuations are calculated for arbitrary velocity distribution functions of plasma particles with allowance for electron collisions. It is shown that quasi-periodic oscillations with two characteristic scales can be present in the spectrum of the plasma line. The smaller scale is due to the wellknown effect of discretization of the spectrum of Langmuir fluctuations in a plasma density well. The larger scale is associated with the generation of scattered waves in two spatial regions and subsequent interference of these waves at the exit from the density well. Oscillations with this scale are more stable under unsteady plasma conditions and can be more often observed in experiments. The results of this work can be used to experimentally determine the plasma parameters, such as the electron collision frequency and the size and lifetime of the plasma density well.