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Author Robinson, P. A. ♦ Wouters, M. J. ♦ Broderick, N. G.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PLASMA PHYSICS AND FUSION ♦ WAVE PROPAGATION ♦ ENERGY TRANSFER ♦ PLASMA WAVES ♦ TURBULENCE ♦ NUCLEATION ♦ RESONANCE ♦ WAVE PACKETS ♦ EIGENSTATES
Abstract Study of Langmuir collapse thresholds shows that they have little polarization dependence and that moving packets have the lowest thresholds in the undamped case. However, incorporation of damping into the density response inhibits collapse of packets moving at more than a small fraction of the sound speed. Investigation of energy transfer to packets localized in density wells{emdash}the nucleation process{emdash}shows that at most a few trapped states can exist and that energy transfer is most effective when there is a single barely-trapped state. Coupled with an argument that closely packed wave packets have lower collapse thresholds, this argument yields an estimate of the number density of localized nucleating states in a turbulent plasma. It also leads to a simple and direct semiquantitative estimate of the collapse threshold. All these results are in accord with previous numerical simulations incorporating ion-sound damping, which show a preponderance of slow-moving or stationary packets with little or no intrinsic polarization dependence of thresholds. Likewise, the number densities obtained are in good agreement with simulation values, and the simple estimate of the threshold is semiquantitatively correct. The extent of the agreement supports the nucleation scenario with close-packed nucleation sites in the turbulent state. {copyright} {ital 1996 American Institute of Physics.}
ISSN 1070664X
Educational Use Research
Learning Resource Type Article
Publisher Date 1996-01-01
Publisher Place United States
Journal Physics of Plasmas
Volume Number 3
Issue Number 1


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