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Ion acoustic wave

An ion acoustic wave is a longitudinal oscillation of the ions (and the electrons) in an unmagnetized plasma or in a magnetized plasma parallel to the magnetic field. The waves are dispersionless with a speed given by

v_s = \sqrt{\frac{\gamma_eZkT_e+\gamma_ikT_i}{M}}

In this equation k is Boltzmann's constant, M is the mass of the ion, Z is its charge, Te is the temperature of the electrons and Ti is the temperature of the ions. Normally γe is taken to be unity, on the grounds that the thermal conductivity of electrons is large enough to keep them isothermal on the time scale of ion acoustic waves, and γi is taken to be 3, corresponding to one-dimensional motion. In many plasmas, the electrons are much hotter than the ions, in which case the second term in the numerator can be ignored.

See also

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ion_acoustic_wave". A list of authors is available in Wikipedia.
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