ALPHA PARTICLE TRANSPORT IN A FIELD-REVERSED CONFIGURATION PLASMA (MULTI-GROUP, STOCHASTICITY, HEATING, FUSION)
Abstract
The behavior of the fusion-produced alpha motion and the effect of the alpha transport on a Field-Reversed Configuration (FRC) have been studied. A new method has been suggested to determine the particle orbit in an effective potential field qualitatively. A multi-group technique has been developed to analyze the alpha transport. The curvature of the effective potential field can be served as an index to indicate the tendency of stochasticity of the particle motion with respect to the particle energy. When a particle moves into a negative curvature potential field, the tendency of stochasticity increases, and the stochastic motion depends on whether or not the particle can overcome this tendency. For a confined particle motion in a two-dimensional potential field, if the turning points stay inside the positive curvature potential region, then it has regular motion. Otherwise, the stochastic motions are dominate. The comparison of this method and the previous numerical studies shows that this method is well verified and more simpler and effective than the previous methods. It is found that most of the alpha motions inside the confined region of an FRC are stochastic. Based on this result, the multi-group method has been established and analyzed for the alpha transport. Two equilibrium FRCs, the Hill's vortex and a racetrack-like configuration, are introduced for these studies. The results show that a significant amount of alpha energy remains in the plasma. The Hill's vortex model has more potential than the racetrack-like model, because of the high heating rate in the beginning of the Hill's vortex model. The parametric studies of the Hill's vortex model show that the elongation factor has no effect on the confinement time, the plasma temperature has significant effect on the alpha heating rate, and the high magnetic field, 20T, has a rapid increase of the heating rate than the 6T or 10T cases. The comparison with the previous works shows that this multi-group method is an accurate and efficient method.
Degree
Ph.D.
Subject Area
Nuclear physics
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