# Waves in plasmas

Waves in plasmas

Waves in plasmas are an interconnected set of particles and fields which propagates in a periodically repeating fashion. A plasma is a quasineutral, electrically conductive fluid. In the simplest case, it is composed of electrons and a single species of positive ions, but it may also contain multiple ion species including negative ions as well as neutral particles. Due to its electrical conductivity, a plasma couples to electric and magnetic fields. This complex of particles and fields supports a wide variety of waves.

Terminology and classification

Waves in plasmas can be classified as electromagnetic or electrostatic according to whether or not there is an oscillating magnetic field. Applying Faraday's law of induction to plane waves, we find $mathbf\left\{k\right\} imes ilde\left\{mathbf\left\{E=omega ilde\left\{mathbf\left\{B$, implying that an electrostatic wave must be purely longitudinal. An electromagnetic wave, in contrast, must have a transverse component, but may also be partially longitudinal.

Waves can be further classified by the oscillating species. In most plasmas of interest, the electron temperature is comparable to or larger than the ion temperature. This fact, coupled with the much smaller mass of the electron, implies that the electrons are much faster than the ions. An electron mode depends on the mass of the electrons, but the ions may be assumed to be infinitely massive, i.e. stationary. An ion mode depends on the ion mass, but the electrons are assumed to be massless and to redistribute themselves instantaneously according to the Boltzmann relation. Only rarely, e.g. in the lower hybrid oscillation, will a mode depend on both the electron and the ion mass.

The various modes can also be classified according to whether they propagate in an unmagnetized plasma or parallel, perpendicular, or oblique to the stationary magnetic field. Finally, for perpendicular electromagnetic electron waves, the perturbed electric field can be parallel or perpendicular to the stationary magnetic field.

* [http://www.hmo.ac.za/old_site/Space_Physics/tut/tut.html The Plasma Tutorial]

References

Swanson, D.G. Plasma Waves (2003). 2nd edition.Stix, Thomas Howard. Waves in Plasmas (1992).

ee also

* Magnetohydrodynamic waves

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Ondas en plasmas — Las ondas en plasmas son un conjunto interelacionado de partículas y campos que se propagan en una forma repetitiva periódica. Un plasma es un fluido conductor de la electricidad casi neutro. En su forma más simple, está formado por electrones e… …   Wikipedia Español

• Magnetohydrodynamics — For the academic journal, see Magnetohydrodynamics (journal). Magnetohydrodynamics (MHD) (magneto fluid dynamics or hydromagnetics) is an academic discipline which studies the dynamics of electrically conducting fluids. Examples of such fluids… …   Wikipedia

• M. Salimullah — Professor M. Salimullah, born on January 5, 1949 at Dhaka, Bangladesh, is Dean, Faculty of Physical and Mathematical Sciences and Chairman of Department of Physics in Jahangirnagar University, Bangladesh. passed B.Sc.(Hons) and M.Sc.(Thesis) in… …   Wikipedia

• Self-focusing — is a non linear optical process induced by the change in refractive index of materials exposed to intense electromagnetic radiation. [Cumberbatch, E. Self focusing in Non linear optics , J. Inst. Maths Applics 6, 250 (1970)] Mourou, G. A. et al.… …   Wikipedia

• 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. The frequency only depends weakly on the wavelength. The quasiparticle… …   Wikipedia

• Corona — This article is about the astronomical term. For other uses, see Corona (disambiguation). During a total solar eclipse, the solar corona can be seen with the naked eye. A corona is a type of plasma atmosphere of the Sun or other celestial body,… …   Wikipedia

• Coronal seismology — is a technique of studying the plasma of the Sun s corona with the use of magnetohydrodynamic (MHD) waves and oscillations. Magnetohydrodynamics studies the dynamics of electrically conducting fluids in this case the fluid is the coronal plasma.… …   Wikipedia

• Magnetosonic wave — A magnetosonic wave (also magnetoacoustic wave) is a longitudinal wave[1] of ions (and electrons) in a magnetized plasma propagating perpendicular to the stationary magnetic field. The wave is dispersionless with a phase velocity ω/k given by ,… …   Wikipedia

• Ion acoustic wave — An ion acoustic wave is a longitudinal oscillation of the ions (and the electrons) much like acoustic waves traveling in neutral gas. However, because the waves propagate through positively charged ions, ion acoustic waves can interact with their …   Wikipedia

• Alfvén , Hannes Olof Gösta — (1908–1995) Swedish physicist Alfvén, who was born in Norrkoeping, Sweden, was educated at the University of Uppsala where he received his PhD in 1934. He subsequently worked at the Royal Institute of Technology, Stockholm, where he served as… …   Scientists