Drift waves

In plasma physics, a drift wave (sometimes known as drift-wave instability or drift instability) is a type of magnetohydrodynamic instability that is driven by a pressure gradient within a plasma. The drift wave typically propagates across the pressure gradient and is perpendicular to the magnetic field. It can occur in relatively simple configurations such as in a column of plasma with a non-uniform density but a straight magnetic field.[1] The drift waves are driven by the thermal expansion of the plasma and responsible for the transport of particles, energy and momentum along magnetic field lines.[2]

The characteristic frequency associated with drift waves involving electron flow[3] is given by

${\displaystyle \omega ^{*}=k_{\perp }\left(-{\frac {k_{B}T_{e}}{eB_{0}}}\nabla n_{0}\right)}$,

where ${\displaystyle k_{\perp }}$ is the wavenumber perpendicular to the pressure gradient of the plasma, ${\displaystyle k_{B}}$ is the Boltzmann constant, ${\displaystyle T_{e}}$ is the electron temperature, ${\displaystyle e}$ is the elementary charge, ${\displaystyle B_{0}}$ is the background magnetic field and ${\displaystyle \nabla n_{0}}$ is the density gradient of the plasma.