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 equations which describe these waves possess a number of solutions, including ion-acoustic solitary waves,^[1] and are roughly analogous to modons.^[2]

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.^[3] Drift wave turbulence is responsible for the transport of particles, energy and momentum across magnetic field lines.^[4]

The characteristic frequency associated with drift waves involving electron flow^[5] is given by $${\displaystyle \omega ^{*}=k_{\perp }\left(-{\frac {k_{B}T_{e}}{eB_{0}}}{\frac {\nabla n_{0}}{n_{0}}}\right),}$$ 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 number density gradient of the plasma.

References

1. Meiss, J. D.; Horton, W. (1983-04-01). "Solitary drift waves in the presence of magnetic shear". The Physics of Fluids. 26 (4): 990–997. doi:10.1063/1.864251. ISSN 0031-9171.
2. Swaters, Gordon E. (1986-05-01). "Stability conditions anda prioriestimates for equivalent-barotropic modons". The Physics of Fluids. 29 (5): 1419–1422. doi:10.1063/1.865658. ISSN 0031-9171.
3. Goldston, Robert J.; Rutherford, Paul H. (1995). "21. Drift waves and instabilities". Introduction to plasma physics. Bristol, UK: Institute of Physics. ISBN 0-7503-0325-5. OCLC 33079555.
4. Horton, W. (1999). "Drift waves and transport". Reviews of Modern Physics. 71 (3): 735–778. Bibcode:1999RvMP...71..735H. doi:10.1103/RevModPhys.71.735. hdl:2152/61083. ISSN 0034-6861. S2CID 122400874.
5. Chen, Francis F. (2016). "6.8 Resistive Drift Waves". Introduction to plasma physics and controlled fusion (3rd ed.). Cham. ISBN 978-3-319-22309-4. OCLC 933392530.