ELMs and the H-mode Pedestal in NSTX

Maingi, R. ; Sabbagh, S.A. ; Bush, C.E. ; Fredrickson, E.D. ; Menard, J.E. ; Stutman, D. ; Tritz, K. ; Bell, M.G. ; Bell, R.E. ; Boedo, J.A. ; Gates, D.A. ; Johnson, D.W. ; Kaita, R. ; Kaye, S.M. ; Kugel, H.W. ; LeBlanc, B.P. ; Mueller, D. ; Raman, R. ; Roquemore, A.L. ; Soukhanovskii, V.A. ; Stevenson, T.

Princeton University. Plasma Physics Laboratory.

关键词: Bootstrap Current;    70 Plasma Physics And Fusion Technology;    Spherical Torus;    Edge Plasma;    Containment;   

DOI  :  10.2172/828497
RP-ID  :  PPPL-3984
RP-ID  :  AC02-76CH03073
RP-ID  :  828497

美国|英语

来源: UNT Digital Library

【 摘 要 】

We report on the behavior of ELMs in NBI-heated H-mode plasmas in NSTX. It is observed that the size of Type I ELMs, characterized by the change in plasma energy, decreases with increasing density, as observed at conventional aspect ratio. It is also observed that the Type I ELM size decreases as the plasma equilibrium is shifted from a symmetric double-null toward a lower single-null configuration. Type III ELMs have also been observed in NSTX, as well as a high-performance regime with small ELMs which we designate Type V. These Type V ELMs are consistent with high bootstrap current operation and density approaching Greenwald scaling. The Type V ELMs are characterized by an intermittent n=1 MHD mode rotating counter to the plasma current. Without active pumping, the density rises continuously through the Type V phase. However, efficient in-vessel pumping should allow density control, based on particle containment time estimates.