ISSN:
1573-8620
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Abstract Experiments are described on the collisionless propagation of heat in a plasma along the magnetic field. Thermal waves can be propagated in a medium whose thermal conductivity is a power function of the temperature. In a collisionless plasma, where the mean free path of particles is much greater than all typical lengths, in particular the length of the equipment, the heat must be propagated by a different method. Experiments to study this phenomenon showed that heat is propagated along the magnetic field with velocity exceeding that of ion-acoustic velocity (I. A. Velocity), and that the spatial width of the thermal disturbance is much less than the mean free path. Heat is propagated because hot electrons are replaced by cold [1]. Noise was observed experimentally in the vicinity of the ion plasma frequency and an estimate of its intensity was obtained. Theoretical discussion showed that the I. A. Velocity instability which develops at the wave front leads to collective friction of the cold electrons with the ions and makes it possible to find the effective collision frequency. It was also shown theoretically that, in accordance with experiment, noise is localized near ωpi, and the level agrees with that obtained experimentally. The phenomenon can be pictured as follows: hot electrons expanding into the region occupied by cold electrons and ions create an electric field. Cold electrons, accelerating in this field, oscillate the I. A. Velocity. This instability leads to heating of the electrons and the appearance of collective friction which forms the heat front.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00853981
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