In physics

Physics

Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

, Landau damping, named after its discoverer, the eminent Soviet physicist Lev Davidovich Landau, is the effect of damping

Damping

In physics, damping is any effect that tends to reduce the amplitude of oscillations in an oscillatory system, particularly the harmonic oscillator.In mechanics, friction is one such damping effect...

 (exponential decrease as a function of time) of longitudinal space charge waves

Plasma oscillation

Plasma oscillations, also known as "Langmuir waves" , are rapid oscillations of the electron density in conducting media such as plasmas or metals. The oscillations can be described as an instability in the dielectric function of a free electron gas. The frequency only depends weakly on the...

 in plasma

Plasma (physics)

In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

 or a similar environment. This phenomenon prevents an instability from developing, and creates a region of stability in the parameter space

Parameter space

In science, a parameter space is the set of values of parameters encountered in a particular mathematical model. Often the parameters are inputs of a function, in which case the technical term for the parameter space is domain of a function....

. It was later argued by Lynden-Bell

Donald Lynden-Bell

Donald Lynden-Bell CBE FRS is an English astrophysicist, best known for his theories that galaxies contain massive black holes at their centre, and that such black holes are the principal source of energy in quasars. He was a co-recipient, with Maarten Schmidt, of the inaugural Kavli Prize for...

 that a similar phenomenon was occurring in galactic dynamics, where the gas of electrons interacting by electro-static forces is replaced by a "gas of stars" interacting by gravitation forces.
Landau damping occurs due to the energy exchange between a wave

Wave

In physics, a wave is a disturbance that travels through space and time, accompanied by the transfer of energy.Waves travel and the wave motion transfers energy from one point to another, often with no permanent displacement of the particles of the medium—that is, with little or no associated mass...

 with phase velocity and particles in the plasma with velocity approximately equal to , which can interact strongly with the wave.