Non-Markovian diffusion in plasma turbulence
- Department of Electrical Engineering, Texas Tech University, Lubbock, Texas 79409-3102 (United States)
- Department of Physics, University of Saskatchewan, Saskatoon S7N 0W0 (Canada)
Motion of charged particles in electrostatic plasma turbulence is studied analytically and numerically. Analytical study is based on a stochastic differential equation, the generalized Langevin equation, which is derived by the projection operator method with the assumption that the random fluctuation field is a Gaussian and wide sense stationary process. The equation describes the particle velocity as a stochastic process driven by field fluctuations, and is applied to evaluate the velocity diffusion coefficient. The non-Markovian velocity diffusivity is characterized by the retarded turbulent collision term which contributes to the memory effect of the wave--particle interaction. Test-particle numerical experiments are carried out by following trajectories of charged particles in Langmuir turbulence. The observed diffusion coefficient in a relatively strong turbulence deviates from predicted values of the quasilinear and the extended resonance broadening theories. The present non-Markovian formulation explains well such a departure of the diffusion rate.
- OSTI ID:
- 6171007
- Journal Information:
- Physics of Fluids B; (United States), Vol. 5:8; ISSN 0899-8221
- Country of Publication:
- United States
- Language:
- English
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