Higher beta at higher elongation in the DIII-D tokamak

E. A. Lazarus, Ming-Sheng Chu, J. R. Ferron, F. J. Helton, J. T. Hogan, A. G. Kellman, L. L. Lao, J. B. Lister, T. H. Osborne, R. Snider, E. J. Strait, T. S. Taylor, A. D. Turnbull

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69 引文 斯高帕斯(Scopus)


A theoretical and experimental evaluation of axisymmetric stability and axisymmetric control has led to a modification of the vertical position control in the DIII-D tokamak, which now allows operation to within a few percent of the ideal magnetohydrodynamic (MHD) n = 0 limit. It is found that the onset the departure from rigid shift behavior in D-shaped plasmas limits plasma elongation to 2.5 in DIII-D. The possibility of avoiding the vertical instability in future tokamaks with highly elongated plasmas is discussed. Recent experiments have focused on utilizing this capability for axisymmetric control to construct plasma shapes optimized to increase the achievable beta. Operation near the axisymmetric stability limit allows an increase in the achieved normalized current Ip/aBT, where Ip is the total plasma current, a is the minor radius, and BT is the toroidal field. Based on stability calculations, an equilibrium was developed to achieve marginal stability simultaneously to axisymmetric, kink, and ballooning instabilities. In the experiment, the shape was altered to higher elongation during the high-beta phase as the current profile broadened. A record high beta for DIII-D of 11% was achieved. The high-beta phase of the discharge lasted 40 msec, approximately one confinement time.

頁(從 - 到)2220-2229
期刊Physics of Fluids B
出版狀態Published - 1991 一月 1

All Science Journal Classification (ASJC) codes

  • 計算力學
  • 凝聚態物理學
  • 材料力學
  • 物理與天文學 (全部)
  • 流體流動和轉移過程


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