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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 18:30 |
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Conference: Bucharest University Faculty of Physics 2022 Meeting
Section: Theoretical Physics and Applied Mathematics
Title:
Effects of non-Gaussianity on turbulent transport in magnetized plasmas and astrophysical systems
Authors:
Ligia POMÂRJANSCHI (1), Dragoș Iustin PALADE (2)
Affiliation:
1) Faculty of Physics, University of Bucharest, Romania
2) National Institute for Laser, Plasma & Radiation Physics, Romania
E-mail
ligiapomarjanschi@gmail.com
Keywords:
turbulence, intermittency, transport
Abstract:
The electric fields in fusion plasmas and the magnetic fields in astrophysical media are known to exhibit strong turbulent features. Consequently, the turbulence leads to non-diffusive, anomalous transport of charged particles and cosmic rays. The relation between turbulent fields and transport is usually investigated under the assumption of Gaussianity of the former which is valid only to an approximate degree. In the present work we go beyond the standard approach and consider how non-Gaussian turbulent fields affect the transport of ions in tokamak plasmas and the cosmic-ray wandering in astrophysical space.
The problem is investigated within a statistical description using two methods: the Decorrelation Trajectory Method [1] and the Direct Numerical Simulation method [2]. We use fully non-linear numerical simulations to evaluate the relation between diffusion coefficients and the parameters of turbulence. Complementary, analytical estimations are constructed which turn out to be in line with the numerical results.
References:
[1] M. Vlad, F. Spineanu, J. H. Misguich, and R. Balescu, Diffusion with intrinsic trapping in two-dimensional incompressible stochastic velocity fields, Phys. Rev. E 58, 7359 – Published 1 December 1998
[2] D.I. Palade, M. Vlad, Fast generation of Gaussian random fields for direct numerical simulations of stochastic transport, Statistics and Computing volume 31, Article number: 60 (2021)
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