Abstract Details

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macnab_icc06.pdf2006-02-20 11:52:09Angus Macnab

FRC Simulations with the NIMROD Code

Author: Angus I.D. Macnab
Submitted: 2005-12-21 13:46:41

Co-authors: D. C. Barnes, R. D. Milroy, C. C. Kim, C. R. Sovinec

Contact Info:
University of Washington
120 AERB Box 352250
Seattle, WA   98195
United States

Abstract Text:
The recently formed Plasma Science and Innovation Center (PSI-Center) is refining the NIMROD code to improve the predictability of computer models. Field Reversed Configurations (FRCs) provide an excellent development tool for extended MHD models because of their highly kinetic nature. The NIMROD code [1] can resolve highly anisotropic heat conduction and viscosity. This combined with its ability to include two-fluid effects allows us to capture more detailed physics than previous calculations. Some initial simulations are focused on 2D (n=0 only) nonlinear two-fluid simulations. In these initial calculations we focus on FRC formation in a theta-pinch, and the physics of spin-up due to end-shorting. Long-term plans include simulating the physics of toroidal field generation during FRC formation – especially when a non-symmetric formation technique (such as a conical theta-pinch) is employed to form a translating FRC. We will also try to simulate the generation of poloidal flow, which together with toroidal field, might be essential in capturing FRC stability [2].
At the same time, a new time-implicit two-fluid version of NIMROD is being verified and applied to the macroscopic stability of a FRC. FRC macro-stability is a problem of intrinsic interest, both from a fundamental and from a practical standpoint, and also presents a unique verification opportunity. Initial n = 1 linear and nonlinear results have reproduced earlier observed [3,4] transition from the “fundamental? MHD internal tilt mode to modes with higher structure along B, with growth rates smaller but comparable to MHD growth rates. Previous long-thin analysis [5] has been extended to capture the features of these modes and results are compared with NIMROD. Modifications to the analysis suggest effects beyond HMHD, which are important for the stability of these modes. Such effects will be incorporated into future NIMROD versions and verified by comparison with the analysis.
1 C.R. Sovinec et al., J. Comp. Phys. 195, 355 (2004)
2 L.C. Steinhauer, Phys. Plasmas 6, 2734 (1999)
3 R.D. Milroy et al., Phys. Fluids B1, 1225 (1989)
4 Elena V. Belova et al., Phys. Plasmas 10, 2361 (2003)
5 D. C. Barnes, Phys. Plasmas 10, 1636 (2003)

Characterization: E1,E5

Comments:

The University of Texas at Austin

Innovative Confinement Concepts Workshop
February 13-16, 2006
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