Nonclassical Transport and Particle-Field Coupling: from Laboratory Plasmas to the Solar Wind

Abstract

Understanding transport of thermal and suprathermal particles is a fundamental issue in laboratory, solar-terrestrial, and astrophysical plasmas. For laboratory fusion experiments, confinement of particles and energy is essential for sustaining the plasma long enough to reach burning conditions. For solar wind and magnetospheric plasmas, transport properties determine the spatial and temporal distribution of energetic particles, which can be harmful for spacecraft functioning, as well as the entry of solar wind plasma into the magnetosphere. For astrophysical plasmas, transport properties determine the efficiency of particle acceleration processes and affect observable radiative signatures. In all cases, transport depends on the interaction of thermal and suprathermal particles with the electric and magnetic fluctuations in the plasma. Understanding transport therefore requires us to understand these interactions, which encompass a wide range of scales, from magnetohydrodynamic to kinetic scales, with larger scale structures also having a role. The wealth of transport studies during recent decades has shown the existence of a variety of regimes that differ from the classical quasilinear regime. In this paper we give an overview of nonclassical plasma transport regimes, discussing theoretical approaches to superdiffusive and subdiffusive transport, wave-particle interactions at microscopic kinetic scales, the influence of coherent structures and of avalanching transport, and the results of numerical simulations and experimental data analyses. Applications to laboratory plasmas and space plasmas are discussed.

From Alfvén waves to kinetic Alfvén waves in an inhomogeneous equilibrium structure

“…Departures of the proton distribution function from the Maxwellian form can be also identified with the temperature anisotropy index [ Perrone et al , ], R ( x , y , t ) = 1− T p ⊥ ( x , y , t )/ T p || ( x , y , t ), T p ⊥ , and T p ∥ being, respectively, the proton perpendicular and parallel temperatures evaluated with respect to the local magnetic field B . Figure shows instantaneous spatial distribution of R ( x , y ) at t = 7.5 (Figures a and b) and at t = 15 (Figures c and d); corresponding to RUN 3 (Figures a and c) and RUN 4 (Figures b and d).…”

“…A detailed description of the numerical method employed to solve equations – can be found in Valentini et al []. We remark that low‐noise Vlasov simulations allow to recover details about the VDFs dynamics [ Servidio et al , ; Greco et al , ; Perrone et al , ; Valentini et al , ; Servidio et al , ].…”

Particle‐in‐cell Experiments Examine Electron Diffusion by Whistler‐mode Waves: 1. Benchmarking With a Cold Plasma

“…Diffusive theories that move beyond the assumption of normal diffusion (sometimes called ‘anomalous diffusion’) have many applications, and not only in space physics (e.g. see Bouchaud & Georges, ; Metzler & Klafter, ; Perrone et al, ; Zaslavsky, ; Zimbardo et al, ). Anomalous diffusion theory essentially allows for the variance of a given parameter X to evolve according to a power‐law for 0< a < ∞ , and for which a <1 denotes ‘sub‐diffusion’, a ≈1 denotes ‘normal diffusion’, and a >1 denotes ‘super‐diffusion’.…”

New Solution of Diffusion–Advection Equation for Cosmic-Ray Transport Using Ultradistributions

“…This equation can be cast as a diffusion one, in which the Laplacian is replaced by a term involving fractional derivatives [18]. See also [19,20,21,22,23,24,25], and references therein. An interesting step towards a more accurate analytical treatment of this problem was recently provided by Litvinenko and Effenberger (LE) in [8].…”