Drift waves

In plasma physics, a drift wave is a type of collective excitation that is driven by a pressure gradient within a magnetised plasma, which can be destabilised by differences between ion and electron motion (then known as drift-wave instability or drift instability). 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. Drift wave turbulence is responsible for the transport of particles, energy and momentum across magnetic field lines.
The characteristic frequency associated with drift waves involving electron flow is given by
formula_1,
where formula_2 is the wavenumber perpendicular to the pressure gradient of the plasma, formula_3 is the Boltzmann constant, formula_4 is the electron temperature, formula_5 is the elementary charge, formula_6 is the background magnetic field and formula_7 is the density gradient of the plasma.