dorsal/arxiv
View SchemaNon-existence of normal tokamak equilibria with negative central current
| Authors | G. W. Hammett, S. C. Jardin, B. C. Stratton |
|---|---|
| Categories | |
| ArXiv ID | physics/0303026 |
| URL | https://arxiv.org/abs/physics/0303026 |
| DOI | 10.1063/1.1608935 |
Abstract
Recent tokamak experiments employing off-axis, non-inductive current drive have found that a large central current hole can be produced. The current density is measured to be approximately zero in this region, though in principle there was sufficient current drive power for the central current density to have gone significantly negative. Recent papers have used a large aspect-ratio expansion to show that normal MHD equilibria (with axisymmetric nested flux surfaces, non-singular fields, and monotonic peaked pressure profiles) can not exist with negative central current. We extend that proof here to arbitrary aspect ratio, using a variant of the virial theorem to derive a relatively simple integral constraint on the equilibrium. However, this constraint does not, by itself, exclude equilibria with non-nested flux surfaces, or equilibria with singular fields and/or hollow pressure profiles that may be spontaneously generated.
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"abstract": "Recent tokamak experiments employing off-axis, non-inductive current drive\nhave found that a large central current hole can be produced. The current\ndensity is measured to be approximately zero in this region, though in\nprinciple there was sufficient current drive power for the central current\ndensity to have gone significantly negative. Recent papers have used a large\naspect-ratio expansion to show that normal MHD equilibria (with axisymmetric\nnested flux surfaces, non-singular fields, and monotonic peaked pressure\nprofiles) can not exist with negative central current. We extend that proof\nhere to arbitrary aspect ratio, using a variant of the virial theorem to derive\na relatively simple integral constraint on the equilibrium. However, this\nconstraint does not, by itself, exclude equilibria with non-nested flux\nsurfaces, or equilibria with singular fields and/or hollow pressure profiles\nthat may be spontaneously generated.",
"arxiv_id": "physics/0303026",
"authors": [
"G. W. Hammett",
"S. C. Jardin",
"B. C. Stratton"
],
"categories": [
"physics.plasm-ph"
],
"doi": "10.1063/1.1608935",
"title": "Non-existence of normal tokamak equilibria with negative central current",
"url": "https://arxiv.org/abs/physics/0303026"
},
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