Potential Methods for Improving Pedestal Temperatures and Fusion Performance

Technical Report · Fri Oct 01 04:00:00 EDT 1999

DOI:https://doi.org/10.2172/13836· OSTI ID:13836

Hammett, G W ^[1]; Kotschenreuther, M; Beer, M A; Dorland, W

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1. Princeton Plasma Physics Laboratory

The physics of the tokamak edge is very complicated, and the scaling of the H-mode transport barrier pedestal has significant uncertainties. Evidence from the largest tokamaks appears to support a model in which the H-mode pedestal width scales linearly with the poloidal gyroradius and the gradient scales with ideal MHD ballooning limits. However, there appears to be significant variability in the data from different tokamaks, including observations on DIII-D that indicate a regime where the pedestal is in second stability and the width is independent of poloidal gyroradius, which would give a more favorable scaling to reactor scales. An important question is the role of the bootstrap current in the pedestal, and another is how far can the improvements in edge stability be p shed with higher triangularity and elongation. Even with the more pessimistic model, where the pedestal width is proportional to the poloidal gyroradius, the results presented here suggest that pedestal temperatures, and thus the fusion performance, may be significantly improved by designs with stronger plasma shaping higher triangularity and elongation, moderate density peaking, and higher magnetic field (and thus reduced size), such as in ARIES-RS, FIRE, and some of the new ITER-RC designs.

• Research Organization: Princeton Plasma Physics Lab., NJ (US)
• Sponsoring Organization: USDOE Office of Energy Research (ER) (US)
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 13836
• Report Number(s): PPPL-3360; AC02-CHO-3073
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BOOTSTRAP CURRENT
DOUBLET-3 DEVICE
EDGE LOCALIZED MODES
ELONGATION
H-MODE PLASMA CONFINEMENT
MAGNETIC FIELDS
PERFORMANCE
TOKAMAK DEVICES