COLLISIONLESS HEATING AND WAVE AMPLIFICATION THROUGH INTERACTION WITH THE DIAMAGNETIC CURRENT.
TEXAS UNIV AUSTIN PLASMA PHYSICS LAB
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Collisionless heating occurs when a magneto-acoustic wave travels at right angles to a magnetic field in a plasma whose density is increasing in the direction of travel. Inclusion of pressure terms in a fluid description leads to an interaction of the wave with the diamagnetic current and a net transfer of energy from the wave to the plasma. The mechanism is, however, completely reversible in the linear approximation. Consequently a wave travelling out of the plasma is amplified, and the plasma loses energy to it. The energy exchange mechanism is not of the Landau type, hence all of the particles of species exchange energy directly with the wave. A description of the time-average heating effects is obtained by expanding the electromagnetic and the fluid equations in a series in mhos. An appropriate generalization of the WKB approximation is used to solve the high-frequency equations. A method for obtaining a net transfer of energy to the plasma from a wave originating externally by varying the magnetic field strength is also discussed along with the effect of the density gradient on other heating mechanisms. Author
- Plasma Physics and Magnetohydrodynamics