Simulations of sawtoothing in a current carrying stellarator

N. A. Roberds; L. Guazzotto; J. D. Hanson; J. L. Herfindal; E. C. Howell; D. A. Maurer; C. R. Sovinec

doi:10.1063/1.4962990

Simulations of sawtoothing in a current carrying stellarator

N. A. Roberds, L. Guazzotto, J. D. Hanson, J. L. Herfindal, E. C. Howell, D. A. Maurer, C. R. Sovinec

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7 Scopus citations

Abstract

Numerical MHD simulations are used to gain insight into how sawteeth are affected by three-dimensional shaping from the Compact Toroidal Hybrid (CTH) stellarator field. CTH is a small stellarator-tokamak hybrid and sawteeth are sometimes seen on soft x-ray signals when operating with tokamak like profiles. We use NIMROD to compute numerical solutions having repeated sawtooth relaxations for a sequence of configurations with increasing helical stellarator field strength. The experimentally observed trend of the sawtooth period decreasing as the helical field strength is increased is recovered in the simulations. Careful attention to numerical convergence was required to obtain the results, and these considerations may be relevant to simulations of other phenomena in devices with non-axisymmetric plasmas such as perturbed tokamaks, RFPs, and stellarators.

Original language	English
Article number	092513
Journal	Physics of Plasmas
Volume	23
Issue number	9
DOIs	https://doi.org/10.1063/1.4962990
State	Published - Sep 1 2016
Externally published	Yes

Funding

This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This work was supported by the U.S. DOE Grant Nos. DE-FG-02-00ER54610 and DE-FG-02-03ER54692.

Funders	Funder number
DOE Office of Science
U.S. DOE	DE-FG-02-00ER54610, DE-FG-02-03ER54692
U.S. Department of Energy	DE-AC02-05CH11231
Office of Science

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10.1063/1.4962990

Cite this

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abstract = "Numerical MHD simulations are used to gain insight into how sawteeth are affected by three-dimensional shaping from the Compact Toroidal Hybrid (CTH) stellarator field. CTH is a small stellarator-tokamak hybrid and sawteeth are sometimes seen on soft x-ray signals when operating with tokamak like profiles. We use NIMROD to compute numerical solutions having repeated sawtooth relaxations for a sequence of configurations with increasing helical stellarator field strength. The experimentally observed trend of the sawtooth period decreasing as the helical field strength is increased is recovered in the simulations. Careful attention to numerical convergence was required to obtain the results, and these considerations may be relevant to simulations of other phenomena in devices with non-axisymmetric plasmas such as perturbed tokamaks, RFPs, and stellarators.",

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AU - Roberds, N. A.

AU - Guazzotto, L.

AU - Hanson, J. D.

AU - Herfindal, J. L.

AU - Howell, E. C.

AU - Maurer, D. A.

AU - Sovinec, C. R.

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AB - Numerical MHD simulations are used to gain insight into how sawteeth are affected by three-dimensional shaping from the Compact Toroidal Hybrid (CTH) stellarator field. CTH is a small stellarator-tokamak hybrid and sawteeth are sometimes seen on soft x-ray signals when operating with tokamak like profiles. We use NIMROD to compute numerical solutions having repeated sawtooth relaxations for a sequence of configurations with increasing helical stellarator field strength. The experimentally observed trend of the sawtooth period decreasing as the helical field strength is increased is recovered in the simulations. Careful attention to numerical convergence was required to obtain the results, and these considerations may be relevant to simulations of other phenomena in devices with non-axisymmetric plasmas such as perturbed tokamaks, RFPs, and stellarators.

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Simulations of sawtoothing in a current carrying stellarator

Abstract

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