Observation of instability-induced current redistribution in a spherical-torus plasma

J. E. Menard; R. E. Bell; D. A. Gates; S. M. Kaye; B. P. Leblanc; F. M. Levinton; S. S. Medley; S. A. Sabbagh; D. Stutman; K. Tritz; H. Yuh

doi:10.1103/PhysRevLett.97.095002

Observation of instability-induced current redistribution in a spherical-torus plasma

J. E. Menard, R. E. Bell, D. A. Gates, S. M. Kaye, B. P. Leblanc, F. M. Levinton, S. S. Medley, S. A. Sabbagh, D. Stutman, K. Tritz, H. Yuh

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86 Scopus citations

Abstract

A motional Stark effect diagnostic has been utilized to reconstruct the parallel current density profile in a spherical-torus plasma for the first time. The measured current profile compares favorably with neoclassical theory when no large-scale magnetohydrodynamic instabilities are present in the plasma. However, a current profile anomaly is observed during saturated interchange-type instability activity. This apparent anomaly can be explained by redistribution of neutral beam injection current drive and represents the first observation of interchange-type instabilities causing such redistribution. The associated current profile modifications contribute to sustaining the central safety factor above unity for over five resistive diffusion times, and similar processes may contribute to improved operational scenarios proposed for ITER.

Original language	English (US)
Article number	095002
Journal	Physical review letters
Volume	97
Issue number	9
DOIs	https://doi.org/10.1103/PhysRevLett.97.095002
State	Published - 2006

All Science Journal Classification (ASJC) codes

General Physics and Astronomy

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10.1103/PhysRevLett.97.095002

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title = "Observation of instability-induced current redistribution in a spherical-torus plasma",

abstract = "A motional Stark effect diagnostic has been utilized to reconstruct the parallel current density profile in a spherical-torus plasma for the first time. The measured current profile compares favorably with neoclassical theory when no large-scale magnetohydrodynamic instabilities are present in the plasma. However, a current profile anomaly is observed during saturated interchange-type instability activity. This apparent anomaly can be explained by redistribution of neutral beam injection current drive and represents the first observation of interchange-type instabilities causing such redistribution. The associated current profile modifications contribute to sustaining the central safety factor above unity for over five resistive diffusion times, and similar processes may contribute to improved operational scenarios proposed for ITER.",

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doi = "10.1103/PhysRevLett.97.095002",

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T1 - Observation of instability-induced current redistribution in a spherical-torus plasma

AU - Menard, J. E.

AU - Bell, R. E.

AU - Gates, D. A.

AU - Kaye, S. M.

AU - Leblanc, B. P.

AU - Levinton, F. M.

AU - Medley, S. S.

AU - Sabbagh, S. A.

AU - Stutman, D.

AU - Tritz, K.

AU - Yuh, H.

PY - 2006

Y1 - 2006

N2 - A motional Stark effect diagnostic has been utilized to reconstruct the parallel current density profile in a spherical-torus plasma for the first time. The measured current profile compares favorably with neoclassical theory when no large-scale magnetohydrodynamic instabilities are present in the plasma. However, a current profile anomaly is observed during saturated interchange-type instability activity. This apparent anomaly can be explained by redistribution of neutral beam injection current drive and represents the first observation of interchange-type instabilities causing such redistribution. The associated current profile modifications contribute to sustaining the central safety factor above unity for over five resistive diffusion times, and similar processes may contribute to improved operational scenarios proposed for ITER.

AB - A motional Stark effect diagnostic has been utilized to reconstruct the parallel current density profile in a spherical-torus plasma for the first time. The measured current profile compares favorably with neoclassical theory when no large-scale magnetohydrodynamic instabilities are present in the plasma. However, a current profile anomaly is observed during saturated interchange-type instability activity. This apparent anomaly can be explained by redistribution of neutral beam injection current drive and represents the first observation of interchange-type instabilities causing such redistribution. The associated current profile modifications contribute to sustaining the central safety factor above unity for over five resistive diffusion times, and similar processes may contribute to improved operational scenarios proposed for ITER.

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JO - Physical review letters

JF - Physical review letters

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Observation of instability-induced current redistribution in a spherical-torus plasma

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