-Limiting MHD instabilities in improved-performance NSTX spherical torus plasmas

Journal Article · Wed Jan 01 00:00:00 EST 2003 · Nuclear Fusion

DOI:https://doi.org/10.1088/0029-5515/43/5/305· OSTI ID:1081835

Menard, J. ^[1]; Peng, Yueng Kay Martin ^[2]

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1. Princeton Plasma Physics Laboratory (PPPL)
2. ORNL

Global magnetohydrodynamic (MHD) stability limits in the National Spherical Torus Experiment (NSTX) have increased significantly recently due to a combination of device and operational improvements. First, more routine H-mode operation with broadened pressure profiles allows access to higher normalized and lower internal inductance. Second, the correction of a poloidal field coil induced error-field has largely eliminated locked tearing modes during normal operation and increased the maximum achievable . As a result of these improvements, peak values have reached (not simultaneously) T = 35%, N = 6.4, N = 4.5, N/li = 10, and P = 1.4. High P operation with reduced tearing activity has allowed a doubling of discharge pulse-length to just over 1 s with sustained periods of N 6 above the ideal no-wall limit and near the with-wall limit. Details of the -limit scalings and -limiting instabilities in various operating regimes are described.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1081835
• Journal Information: Nuclear Fusion, Vol. 43, Issue 5; ISSN 0029--5515
• Country of Publication: United States
• Language: English