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Abstract

As a demonstration of the connection between plasma fluid and kinetic behaviour, the general solution is outlined for electron oscillations, covering the entire range of kh-D where k is the wave number and h-D the Debye distance. Charge separation produces an electric field which limits the electron excursions, thus acting as a "fluid binding force". In the limit kh-D >> 1 this force becomes weak and the electron gas exhibits a free streaming behaviour which cannot be treated in terms of conventional normal mode analysis and macroscopic fluid equations. Thus, the moment equations become irrelevant in this case because they do not represent a solution of the Vlasov equation. Free streaming results in phase mixing which has a strong non-resonant kinetic damping effect on the macroscopic features of a plasma disturbance. If instead kh-D << 1, the same binding force becomes strong and makes the electrons behave largely as a macroscopic fluid. In this special case not only the macroscopic fluid-like features of the electron gas are recovered, such as the thermal pressure gradient effects of Tonks-Langmuir and Vlasov, but also those of Landau damping. The latter damping differs from that by phase mixing due to free streaming, in the sense that it is resonant and becomes related to the electric field. Thus, Landau damping comes out as a "subsidiary" kinetic effect in an electron gas which largely behaves as a macroscopic field.

Additional information

Authors: LEHNERT B ROYAL INSTITUTE OF TECHNOLOGY, STOCKHOLM, (SWEDEN), ROYAL INSTITUTE OF TECHNOLOGY, STOCKHOLM, (SWEDEN)
Bibliographic Reference: WRITE TO THE DEPARTMENT OF PLASMA PHYSICS AND FUSION RESEARCH, ROYAL INSTITUTE OF TECHNOLOGY, S-100 44 STOCKHOLM (SWEDEN), MENTIONING REPORT TRITA-PFU-85-05, 1985
Record Number: 1989124042000 / Last updated on: 1987-01-01
Category: PUBLICATION
Available languages: en