Initial experiments at high normalized current in the pegasus toroidal experiment

E. A. Unterberg; D. J. Battaglia; M. W. Bongard; N. W. Eidietis; R. J. Fonck; M. J. Frost; G. D. Garstka; B. A. Kujak-Ford; B. T. Lewicki; B. J. Squires; G. R. Winz

doi:10.1007/s10894-006-9056-z

Initial experiments at high normalized current in the pegasus toroidal experiment

E. A. Unterberg, D. J. Battaglia, M. W. Bongard, N. W. Eidietis, R. J. Fonck, M. J. Frost, G. D. Garstka, B. A. Kujak-Ford, B. T. Lewicki, B. J. Squires, G. R. Winz

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

Initial experiments in the Pegasus ST exhibited an operational limit of I _p I _tf at A 1.15. With new power supplies, discharge control has greatly increased. Equilibria and stability modeling of the high I _p/I _tf regime has produced stable equilibria with I _p/I _tf up to 2 while values of I _p/I _tf approaching 3 show a potential upper bound on stability. A new operating regime has been accessed in recent experiments with the addition of electrostatic plasma sources. Using the sources as a pre-ionization technique, I _p/I _tf values of 1.5 have been accessed at very low toroidal fields. Using the sources as a means for non-inductive startup, values of I _p/I _tf up to 2.3 are attained. The MHD activity in these discharges is characteristically different than ohmic discharges, suggesting the new current sources are modifying the current profile to allow stable discharge evolution at minimal toroidal field.

Original language	English
Pages (from-to)	221-225
Number of pages	5
Journal	Journal of Fusion Energy
Volume	26
Issue number	1-2
DOIs	https://doi.org/10.1007/s10894-006-9056-z
State	Published - Jun 2007
Externally published	Yes

Funding

This work is funded by U.S. Department of Energy Grant DE-FG02-96ER54375.

Funders	Funder number
U.S. Department of Energy	DE-FG02-96ER54375

Keywords

High normalized current
Magnetohydrodynamic stability
Spherical torus
Toroidal field utilization

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10.1007/s10894-006-9056-z

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title = "Initial experiments at high normalized current in the pegasus toroidal experiment",

abstract = "Initial experiments in the Pegasus ST exhibited an operational limit of I p I tf at A 1.15. With new power supplies, discharge control has greatly increased. Equilibria and stability modeling of the high I p/I tf regime has produced stable equilibria with I p/I tf up to 2 while values of I p/I tf approaching 3 show a potential upper bound on stability. A new operating regime has been accessed in recent experiments with the addition of electrostatic plasma sources. Using the sources as a pre-ionization technique, I p/I tf values of 1.5 have been accessed at very low toroidal fields. Using the sources as a means for non-inductive startup, values of I p/I tf up to 2.3 are attained. The MHD activity in these discharges is characteristically different than ohmic discharges, suggesting the new current sources are modifying the current profile to allow stable discharge evolution at minimal toroidal field.",

keywords = "High normalized current, Magnetohydrodynamic stability, Spherical torus, Toroidal field utilization",

author = "Unterberg, {E. A.} and Battaglia, {D. J.} and Bongard, {M. W.} and Eidietis, {N. W.} and Fonck, {R. J.} and Frost, {M. J.} and Garstka, {G. D.} and Kujak-Ford, {B. A.} and Lewicki, {B. T.} and Squires, {B. J.} and Winz, {G. R.}",

year = "2007",

month = jun,

doi = "10.1007/s10894-006-9056-z",

language = "English",

volume = "26",

pages = "221--225",

journal = "Journal of Fusion Energy",

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AU - Unterberg, E. A.

AU - Battaglia, D. J.

AU - Bongard, M. W.

AU - Eidietis, N. W.

AU - Fonck, R. J.

AU - Frost, M. J.

AU - Garstka, G. D.

AU - Kujak-Ford, B. A.

AU - Lewicki, B. T.

AU - Squires, B. J.

AU - Winz, G. R.

PY - 2007/6

Y1 - 2007/6

N2 - Initial experiments in the Pegasus ST exhibited an operational limit of I p I tf at A 1.15. With new power supplies, discharge control has greatly increased. Equilibria and stability modeling of the high I p/I tf regime has produced stable equilibria with I p/I tf up to 2 while values of I p/I tf approaching 3 show a potential upper bound on stability. A new operating regime has been accessed in recent experiments with the addition of electrostatic plasma sources. Using the sources as a pre-ionization technique, I p/I tf values of 1.5 have been accessed at very low toroidal fields. Using the sources as a means for non-inductive startup, values of I p/I tf up to 2.3 are attained. The MHD activity in these discharges is characteristically different than ohmic discharges, suggesting the new current sources are modifying the current profile to allow stable discharge evolution at minimal toroidal field.

AB - Initial experiments in the Pegasus ST exhibited an operational limit of I p I tf at A 1.15. With new power supplies, discharge control has greatly increased. Equilibria and stability modeling of the high I p/I tf regime has produced stable equilibria with I p/I tf up to 2 while values of I p/I tf approaching 3 show a potential upper bound on stability. A new operating regime has been accessed in recent experiments with the addition of electrostatic plasma sources. Using the sources as a pre-ionization technique, I p/I tf values of 1.5 have been accessed at very low toroidal fields. Using the sources as a means for non-inductive startup, values of I p/I tf up to 2.3 are attained. The MHD activity in these discharges is characteristically different than ohmic discharges, suggesting the new current sources are modifying the current profile to allow stable discharge evolution at minimal toroidal field.

KW - High normalized current

KW - Magnetohydrodynamic stability

KW - Spherical torus

KW - Toroidal field utilization

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JO - Journal of Fusion Energy

JF - Journal of Fusion Energy

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ER -

Initial experiments at high normalized current in the pegasus toroidal experiment

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