Equilibrium evolution in oscillating-field current-drive experiments

K. J. McCollam; J. K. Anderson; A. P. Blair; D. Craig; D. J. Den Hartog; F. Ebrahimi; R. O'Connell; J. A. Reusch; J. S. Sarff; H. D. Stephens; D. R. Stone; D. L. Brower; B. H. Deng; W. X. Ding

doi:10.1063/1.3461167

Equilibrium evolution in oscillating-field current-drive experiments

K. J. McCollam, J. K. Anderson, A. P. Blair, D. Craig, D. J. Den Hartog, F. Ebrahimi, R. O'Connell, J. A. Reusch, J. S. Sarff, H. D. Stephens, D. R. Stone, D. L. Brower, B. H. Deng, W. X. Ding

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Abstract

Oscillating-field current drive (OFCD) is a proposed method of steady-state toroidal plasma sustainment in which ac poloidal and toroidal loop voltages are applied to produce a dc plasma current. OFCD is added to standard, inductively sustained reversed-field pinch plasmas in the Madison Symmetric Torus [R. N. Dexter, Fusion Technol. 19, 131 (1991)]. Equilibrium profiles and fluctuations during a single cycle are measured and analyzed for different relative phases between the two OFCD voltages and for OFCD off. For OFCD phases leading to the most added plasma current, the measured energy confinement is slightly better than that for OFCD off. By contrast, the phase of the maximum OFCD helicity-injection rate also has the maximum decay rate, which is ascribed to transport losses during discrete magnetic-fluctuation events induced by OFCD. Resistive-magnetohydrodynamic simulations of the experiments reproduce the observed phase dependence of the added current.

Original language	English (US)
Article number	082506
Journal	Physics of Plasmas
Volume	17
Issue number	8
DOIs	https://doi.org/10.1063/1.3461167
State	Published - Aug 2010
Externally published	Yes

All Science Journal Classification (ASJC) codes

Condensed Matter Physics

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10.1063/1.3461167

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title = "Equilibrium evolution in oscillating-field current-drive experiments",

abstract = "Oscillating-field current drive (OFCD) is a proposed method of steady-state toroidal plasma sustainment in which ac poloidal and toroidal loop voltages are applied to produce a dc plasma current. OFCD is added to standard, inductively sustained reversed-field pinch plasmas in the Madison Symmetric Torus [R. N. Dexter, Fusion Technol. 19, 131 (1991)]. Equilibrium profiles and fluctuations during a single cycle are measured and analyzed for different relative phases between the two OFCD voltages and for OFCD off. For OFCD phases leading to the most added plasma current, the measured energy confinement is slightly better than that for OFCD off. By contrast, the phase of the maximum OFCD helicity-injection rate also has the maximum decay rate, which is ascribed to transport losses during discrete magnetic-fluctuation events induced by OFCD. Resistive-magnetohydrodynamic simulations of the experiments reproduce the observed phase dependence of the added current.",

author = "McCollam, \{K. J.\} and Anderson, \{J. K.\} and Blair, \{A. P.\} and D. Craig and \{Den Hartog\}, \{D. J.\} and F. Ebrahimi and R. O'Connell and Reusch, \{J. A.\} and Sarff, \{J. S.\} and Stephens, \{H. D.\} and Stone, \{D. R.\} and Brower, \{D. L.\} and Deng, \{B. H.\} and Ding, \{W. X.\}",

year = "2010",

month = aug,

doi = "10.1063/1.3461167",

language = "English (US)",

volume = "17",

journal = "Physics of Plasmas",

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AU - McCollam, K. J.

AU - Anderson, J. K.

AU - Blair, A. P.

AU - Craig, D.

AU - Den Hartog, D. J.

AU - Ebrahimi, F.

AU - O'Connell, R.

AU - Reusch, J. A.

AU - Sarff, J. S.

AU - Stephens, H. D.

AU - Stone, D. R.

AU - Brower, D. L.

AU - Deng, B. H.

AU - Ding, W. X.

PY - 2010/8

Y1 - 2010/8

N2 - Oscillating-field current drive (OFCD) is a proposed method of steady-state toroidal plasma sustainment in which ac poloidal and toroidal loop voltages are applied to produce a dc plasma current. OFCD is added to standard, inductively sustained reversed-field pinch plasmas in the Madison Symmetric Torus [R. N. Dexter, Fusion Technol. 19, 131 (1991)]. Equilibrium profiles and fluctuations during a single cycle are measured and analyzed for different relative phases between the two OFCD voltages and for OFCD off. For OFCD phases leading to the most added plasma current, the measured energy confinement is slightly better than that for OFCD off. By contrast, the phase of the maximum OFCD helicity-injection rate also has the maximum decay rate, which is ascribed to transport losses during discrete magnetic-fluctuation events induced by OFCD. Resistive-magnetohydrodynamic simulations of the experiments reproduce the observed phase dependence of the added current.

AB - Oscillating-field current drive (OFCD) is a proposed method of steady-state toroidal plasma sustainment in which ac poloidal and toroidal loop voltages are applied to produce a dc plasma current. OFCD is added to standard, inductively sustained reversed-field pinch plasmas in the Madison Symmetric Torus [R. N. Dexter, Fusion Technol. 19, 131 (1991)]. Equilibrium profiles and fluctuations during a single cycle are measured and analyzed for different relative phases between the two OFCD voltages and for OFCD off. For OFCD phases leading to the most added plasma current, the measured energy confinement is slightly better than that for OFCD off. By contrast, the phase of the maximum OFCD helicity-injection rate also has the maximum decay rate, which is ascribed to transport losses during discrete magnetic-fluctuation events induced by OFCD. Resistive-magnetohydrodynamic simulations of the experiments reproduce the observed phase dependence of the added current.

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JO - Physics of Plasmas

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Equilibrium evolution in oscillating-field current-drive experiments

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