Optimization of negative central shear discharges in shaped cross sections
- CRPP-EPFL, Lausanne (Switzerland)
Magnetohydrodynamic (MHD) stability analyses of Negative Central Shear (NCS) equilibria have revealed a new understanding of the limiting MHD instabilities in NCS experiments. Ideal stability calculations show a synergistic effect between cross section shape and pressure profile optimization; strong shaping and broader pressure independently lead to moderately higher {Beta} limits, but broadening of the pressure profile in a strongly dee-shaped cross- section leads to a dramatic increase in the ideal {Beta} limit. Localized resistive interchange (RI) modes can be unstable in the negative shear region and are most restrictive for peaked pressure profiles. Resistive global modes can also be destabilized significantly below the ideal P limit. Experiments largely confirm the general trends, and diagnostic measurements and numerical stability calculations are found to be in good qualitative agreement. Observed disruptions in NCS discharges with L-mode edge and strongly peaked pressure, appear to be initiated by interactions between the RI, and the global ideal and resistive modes.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC03-89ER51114; FG03-95ER54294; FG05-88ER53266; W-7405-ENG-48
- OSTI ID:
- 455543
- Report Number(s):
- GA-A-22482; CONF-950956-6; ON: DE97003829; TRN: 97:011988
- Resource Relation:
- Conference: 16. IEEE/NPSS symposium on fusion engineering, Champaign, IL (United States), 30 Sep - 5 Oct 1995; Other Information: PBD: Oct 1996
- Country of Publication:
- United States
- Language:
- English
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