Dynamic modelling of lower hybrid current drive

A dynamic computational model of lower hybrid current drive in the presence of an electric field is described and some results are given. Details of geometry, plasma profiles and circuit equations are treated carefully. Two dimensional velocity space effects are approximated in a one dimensional Fokker-Planck treatment. The model is unable to approximate experimental results in some cases characterized by low density, low current, high aspect ratio and a launched spectrum at high phase velocity relative to the thermal velocity. In other cases, qualitative agreement with measurements is found. A simple formula already in the literature appears to determine whether agreement of model and experiment will be good or poor. Application to an experimental discharge in which q(0) is raised above unity shows an appropriate time-scale. Computation of a planned effort for high beta suggests potential success

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