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 oscillations can be described as an instability in the dielectric function of a free electron gas. The frequency only depends weakly on the wavelength of the oscillation. The
quasiparticle resulting from the
quantization of these oscillations is the
plasmon.