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NIMROD Simulations of the Levitated Dipole Experiment
| Author: | Kesner J. |
| Coauthor: | C.R. Sovinec |
| Institution : | MIT |
| Abstract text: | Theory predicts that the closed field line geometry of a levitated dipole configuration can support MHD stable plasmas at high beta values when the pressure gradient does not exceed a critical value. For sufficiently strong heating this stability limit would be violated and we expect instability to develop, leading non-linearly to the formation of convective cells. The NIMROD code [1] permits the study of the non-linear development of MHD modes, including resistive effects. NIMROD simulations have been performed for the LDX geometry. The simulations indicate the onset of MHD activity for sufficient heating power and for realistic (non ideal) heating profiles. In the presence of instability the plasma is seen to exhibit large scale convective flows but it remains centered in the vacuum chamber, anchored by the internal ring. For sufficient heating power we observe that we can exceed the ideal pressure limit in the presence of large-scale convection.
[1] C.R. Sovinec and the Nimrod team, Journal of Computational Physics, Vol. 195, p. 355 (2004).
In collaboration with D.T. Garnier, A. Hansen, M. Mauel, Columbia University.
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