-Limiting MHD instabilities in improved-performance NSTX spherical torus plasmas
- Princeton Plasma Physics Laboratory (PPPL)
- 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
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