Tearing-mode transport model in the reversed field pinch concept
Author(s)Bruno, Antonio, 1972-
Massachusetts Institute of Technology. Dept. of Nuclear Engineering.
Jeffrey P. Freidberg.
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In this thesis, a self-consistent model for analyzing the transport performance of a Reversed Field Pinch (RFP)-type of thermonuclear fusion reactor has been developed. The study has been focused on determining equilibrium configurations which describe a plasma evolution dominated by particular instabilities originated by plasma electrical resistivity (tearing-, or resistive interchange, modes). The ultimate goal is to provide a model of transport scaling in an RFP which can evaluate the global parameters describing the plasma confinement performance. Starting from a magnetic field configuration essentially given by Taylor's relaxation model, the self-consistent pressure profile is determined by assuming that the ohmic heating source raises the plasma pressure until the profile is locally marginally stable to tearing modes. A critical point here is the long held belief that an RFP, because of its bad curvature, would always be unstable to tearing or resistive interchange modes; that is, no marginally stable state exists. This belief turns out to be untrue. The basis for this statement is a careful ordering of the resistive layer dynamics, showing that thermal conductivity dominates over convection and compressibility. Thus, the use of the adiabatic equation of state in earlier work is not accurate for an RFP.(cont.) As a result, tearing and interchange modes can indeed be stabilized in an RFP. In this model, a proper, selfconsistent definition of tearing-mode marginality has been used as a prescription for building the pressure profile. The actual numerical determination of the marginally stable profiles can be solved by using state-of-the-art personal computers. It is worth emphasizing that there are no free parameters in the model. Point checks indicate reasonable agreement with typical experimental data. Parametric numerical studies are also shown, spanning the operational space of RFP experiments, and finally providing the tearing mode transport scaling relations for the global confinement parameters. Comparisons with experiments as well as other transport models are shown.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2002.Includes bibliographical references (leaves 185-188).
DepartmentMassachusetts Institute of Technology. Dept. of Nuclear Engineering.
Massachusetts Institute of Technology