Non-existence of Normal Tokamak Equilibria with Negative Central Current | |
Hammett, G.W. ; Jardin, S.C. ; Stratton, B.C. | |
Princeton University. Plasma Physics Laboratory. | |
关键词: Non-Inductive Current Drive; Equilibrium, Mhd-Toroidal; 70 Plasma Physics And Fusion Technology; Virial Theorem; Current Density; | |
DOI : 10.2172/812029 RP-ID : PPPL-3788 RP-ID : AC02-76CH03073 RP-ID : 812029 |
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美国|英语 | |
来源: UNT Digital Library | |
【 摘 要 】
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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