Charged particle dynamics in the presence of non-Gaussian Lévy electrostatic fluctuations

• Full orbit dynamics of charged particles in a 3-dimensional helical magnetic field in the presenceof a-stable Levy electrostatic fluctuations and linear friction modeling collisional Coulomb drag isstudied via Monte Carlo numerical simulations. The Levy fluctuations are introduced to model theeffect of non-local transport due to fractional diffusion in velocity space resulting from intermittentelectrostatic turbulence. The probability distribution functions of energy, particle displacements,and Larmor radii are computed and showed to exhibit a transition from exponential decay, in thecase of Gaussian fluctuations, to power law decay in the case of Levy fluctuations. The absolutevalue of the power law decay exponents is linearly proportional to the Levy index a. The observedanomalous non-Gaussian statistics of the particles’ Larmor radii (resulting from outlier transportevents) indicate that, when electrostatic turbulent fluctuations exhibit non-Gaussian Levy statistics,gyro-averaging and guiding centre approximations might face limitations and full particle orbiteffects should be taken into account.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

NATURVETENSKAP  -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)

Nyckelord

Levy fluctuations

Langevin dynamics

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art (ämneskategori)

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