Lecture

Plasma Instabilities: Non-Linear Effects

Graph Chat

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

Description

This lecture delves into the study of a system of three non-linearly coupled waves, exploring the effective energy transfer between them and the concepts of action amplitude and action density. The lecture covers wave energy in dispersive media, deriving solutions for the time evolution of the amplitudes of three resonantly coupled waves. Analytic solutions are expressed in terms of elliptic functions, illustrating saturation mechanisms of parametric instabilities. The closely related topic of Stimulated Raman Scattering (SRS) is carefully examined, providing exercises to derive wave energy related to Transverse Electromagnetic Waves (TEMWs) and Electron Plasma Waves (EPWs).

Official source

Related concepts (32)

Mechanical wave

In physics, a mechanical wave is a wave that is an oscillation of matter, and therefore transfers energy through a medium. While waves can move over long distances, the movement of the medium of transmission—the material—is limited. Therefore, the oscillating material does not move far from its initial equilibrium position. Mechanical waves can be produced only in media which possess elasticity and inertia. There are three types of mechanical waves: transverse waves, longitudinal waves, and surface waves.

Plasma oscillation

Plasma oscillations, also known as Langmuir waves (after Irving Langmuir), are rapid oscillations of the electron density in conducting media such as plasmas or metals in the ultraviolet region. The oscillations can be described as an instability in the dielectric function of a free electron gas. The frequency depends only weakly on the wavelength of the oscillation. The quasiparticle resulting from the quantization of these oscillations is the plasmon. Langmuir waves were discovered by American physicists Irving Langmuir and Lewi Tonks in the 1920s.

Wave

In physics, mathematics, engineering, and related fields, a wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities. Waves can be periodic, in which case those quantities oscillate repeatedly about an equilibrium (resting) value at some frequency. When the entire waveform moves in one direction, it is said to be a traveling wave; by contrast, a pair of superimposed periodic waves traveling in opposite directions makes a standing wave.

Plasma (physics)

Plasma () is one of four fundamental states of matter, characterized by the presence of a significant portion of charged particles in any combination of ions or electrons. It is the most abundant form of ordinary matter in the universe, being mostly associated with stars, including the Sun. Extending to the rarefied intracluster medium and possibly to intergalactic regions, plasma can be artificially generated by heating a neutral gas or subjecting it to a strong electromagnetic field.

Raman scattering

Raman scattering or the Raman effect (ˈrɑːmən) is the inelastic scattering of photons by matter, meaning that there is both an exchange of energy and a change in the light's direction. Typically this effect involves vibrational energy being gained by a molecule as incident photons from a visible laser are shifted to lower energy. This is called normal Stokes Raman scattering. The effect is exploited by chemists and physicists to gain information about materials for a variety of purposes by performing various forms of Raman spectroscopy.

Related lectures (56)

Plasma Waves: Properties & Frequencies MOOC: Plasma Physics: Introduction

Explores the properties of plasma waves, focusing on dispersion, cut-off, resonance frequencies, and wave modes.

Stimulated Scatterings: Nonlinear Fibre Optics

Explores stimulated scatterings in nonlinear fibre optics, covering Brillouin and Raman scattering, spectral characteristics, and power limitations.

Electromagnetic Waves in Plasmas

Covers the behavior of electromagnetic waves in non-magnetized plasmas and the simplification of equations for non-collisional plasmas.

Wave and Particle View

Explores the particle and wave views of energy transport and their mathematical expressions.

Plasma Waves: Propagation and Modes