Date Awarded

1995

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Physics

Advisor

Allen H Boozer

Abstract

A Monte Carlo code has been developed which very efficiently calculates plasma parameters, such as currents, potentials and transport coefficients for a fully three dimensional magnetic field configuration. The code computes the deviation, f, of the exact distribution function, f, from the Maxwellian, {dollar}F\sb{lcub}M{rcub},{dollar} with {dollar}\psi{dollar} the toroidal magnetic flux enclosed by a pressure surface and H the Hamiltonian. The particles in the simulation are followed with a traditional Monte Carlo scheme consisting of an orbit step in which new values for the positions and momenta are obtained and a collision step in which a Monte Carlo equivalent of the Lorentz operator is applied to change the pitch of each particle. Since the {dollar}\delta f{dollar} code calculates only the deviations from the Maxwellian rather than the full distribution function, it is about 10{dollar}\sp4{dollar} times as efficient as other Monte Carlo techniques used to calculate currents in plasmas.;The {dollar}\delta f{dollar} code was used to study the aspect ratio and collisionality dependence of the bootstrap current and two Fourier components of the Pfirsch-Schluter current. It was also used to calculate electric potentials within magnetic surfaces due to the explicit enforcement of the quasi-neutrality condition. The code also calculated transport coefficients for the ions and electrons under various conditions. The agreement between the values predicted by the code for the plasma currents and analytic theory is excellent. The transport parameters calculated for the ions and electrons are in qualitative agreement with values predicted from neoclassical transport theory, including transport induced by a toroidal ripple. The in-surface electric potentials induced by explicitly enforcing the quasi-neutrality condition are too small to significantly enhance transport across the magnetic surfaces.

DOI

https://dx.doi.org/doi:10.21220/s2-j9t0-g494

Rights

© The Author

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