Abstract Details
Abstracts
Author: Scott D. Baalrud
Requested Type: Poster
Submitted: 2017-03-17 17:03:45
Co-authors: J. Daligault
Contact Info:
University of Iowa
213 Van Allen Hall
Iowa City, IA 52242
United States
Abstract Text:
Collisional plasma transport theories, such as Braginskii or neoclassical transport theory, are based on perturbative expansions of the Boltzmann kinetic equation about equilibrium. In these approaches, the magnetic field influences the perturbation of the distribution functions but not the microphysics of binary collisions. This approximation is valid when the length scale of the gyromotion is much longer than the maximum interaction distance between binary interacting particles (the Debye length). Here, it is shown that transport properties fundamentally change in the strongly magnetized regime, defined by the condition that the gyroradius be less than the Debye length. Using molecular dynamics simulations of diffusion and temperature anisotropy relaxation, along with analytic theory that extends the usual Boltmann-based kinetic theory to include a strong magnetic field, four fundamental regimes of plasma transport are identified as magnetic field strength varies. Fundamental properties, such as the scaling of transport coefficients with magnetic field differ in each regime. For example, in the strongly magnetized regime, the cross-field diffusion coefficient is found to scale as $1/B$ rather than the $1/B^2$ scaling of Braginskii transport. It is shown that electrons in many fusion experiments can be in this strongly magnetized regime. The results may have consequences for modeling the collisional component of transport coefficients, such as the electron thermal conductivity.
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