ISSN:
1089-7666
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Past spheromak experiments have experienced poor confinement [Nucl. Fusion 28, 1555 (1988); Phys. Fluids B 2, 115 (1990)] as a result of edge-dominated helicity dissipation due to substantial field error and edge neutral inventory. Recent works have identified the importance of edge helicity loss and its effects on confinement [Phys. Fluids B 2, 115 (1990)]. Herein, the results of the edge helicity dissipation model [Phys. Fluids 30, 1177 (1987)] are applied to determine the relative magnitudes of electric fields during relaxation in spheromaks. This is achieved by quantifying the average electric field in the plasma edge region generated by (a) flux decay and (b) relaxation mechanism(s). It is shown that relaxation electric fields can be as much as three times the flux decay field in the edge. The model also correctly predicts no relaxation electric field when the spheromak is a cold, purely resistively decaying object. In addition, the model provides an estimate for the quantity of magnetic decay power from relaxation, which can be as much as 75% of the total decay power.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.859795
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