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Effective collision frequency due to ion‐acoustic instability: Theory and simulations
Author(s) -
Hellinger Petr,
Trávníček Pavel,
Menietti J. Douglas
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl020028
Subject(s) - collision frequency , physics , electron , instability , collision , ion , scattering , proton , atomic physics , saturation (graph theory) , computational physics , mass ratio , plasma , nuclear physics , mechanics , optics , quantum mechanics , astrophysics , computer security , mathematics , combinatorics , computer science
We study the ion‐acoustic instability driven by a drift between Maxwellian protons and electrons in a nonmagnetized plasma using a Vlasov simulation with the realistic proton to electron mass ratio. Simulation results for similar electron and proton temperatures are in good agreement with predictions. Namely, during the linear and saturation phases the effective collision frequency observed in the simulation is in quantitative agreement with the quasi‐linear predictions. However, previous estimates [ Galeev and Sagdeev , 1984; Labelle and Treumann , 1988] give the effective collision frequency less than one tenth the simulated values. The theoretical and simulation results are in a partial agreement with the simulation work by Watt et al. [2002] who used a non‐realistic mass ratio. After the saturation, the effective collision frequency increases owing to the existence of backward‐propagating ion‐acoustic waves. These waves result from induced scattering on protons and contribute to the anomalous transport of electrons.