Multi-Device Scaling of Neoclassical Tearing Mode Onset with Beta
Description/Abstract
The islands from tearing modes driven unstable and sustained by helically perturbed neo-classical bootstrap current at high beta often provide the practical limit to long-pulse, high confinement tokamak operation [1,2]. The discharges studied are ELMy H-mode single-null divertor (SND) at q{sub 95} {approx}> 3. Periodic sawteeth with m/n = 1/1 and 2/2 are observed to induce m/n = 3/2 neoclassical tearing modes (NTMs) in the tokamaks Asdex-Upgrade [3], DIII-D [4] and JET [5]; confinement can drop by up to 30%, constituting a ''soft'' beta limit. Data for the onset of these modes was obtained by slowly raising beta on a time scale longer than the sawteeth period and observing the beta value at onset. Comparison of the measured critical beta to a model for the critical beta is made in terms of dimensionless parameters. This modeling is then used for extrapolation/prediction to a reactor-grade tokamak.
| Creator/Author: | La Haye, R.J. ; Buttery, R.J. ; Guenter, S. ; Huysmans, G.T.A. ; Wilson, H.R. |
|---|---|
| Publication Date: | 1999 Jul 01 |
| OSTI Identifier: | OSTI ID: 766699 |
| Report Number(s): | GA-A23138 |
| DOE Contract Number: | AC03-99ER54463 |
| Other Number(s): | TRN: US0109257 |
| Resource Type: | Conference |
| Resource Relation: | Conference: 26th European Physical Society Conference on Controlled Fusion and Plasma Physics, Maastricht (NL), 06/14/1999--06/18/1999; Other Information: PBD: 1 Jul 1999 |
| Research Org: | General Atomics, San Diego, CA (US) |
| Sponsoring Org: | US Department of Energy (US) |
| Subject: | 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BOOTSTRAP CURRENT; H-MODE PLASMA CONFINEMENT; DIVERTORS; DOUBLET-3 DEVICE; TEARING INSTABILITY; HIGH-BETA PLASMA; SAWTOOTH OSCILLATIONS; MATHEMATICAL MODELS |
| Country of Publication: | United States |
| Language: | English |
| Format: | Size: 4 pages |
| Availability: | INIS; OSTI as DE00766699 To purchase this media from NTIS, click here |
| Update Date: | 2008 Feb 05 |
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