Open AccessELMs and the H-mode Pedestal in NSTX
Author(s) -
R. Maingi,
S. A. Sabbagh,
C. E. Bush,
E. D. Fredrickson,
J. Ménard,
D. Stutman,
K. Tritz,
M.G. Bell,
R. E. Bell,
J.A. Boedo,
D. Gates,
D. W. Johnson,
R. Kaita,
S. M. Kaye,
H. Kugel,
B.P. LeBlanc,
D. Mueller,
R. Raman,
A. L. Roquemore,
V. Soukhanovskii,
T. Stevenson
Publication year - 2004
Language(s) - English
Resource type - Reports
DOI - 10.2172/828497
Subject(s) - pedestal , plasma , scaling , atomic physics , magnetohydrodynamics , physics , mode (computer interface) , nuclear physics , geometry , mathematics , archaeology , history , computer science , operating system
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