TY - RPRT
TI - Onset of ELMs in JT-60U
AB - The ELMs limiting the energy confinement in JT-60U appear when the heating power is high enough compared to the threshold power for the L-H transition. The ELM-free phase is observed when n-bar{sub e} is lower than the threshold density n-bar{sub e}{sup th}. The threshold density n-bar{sub e}{sup th} increases with (B{sub t}{sup 2}/(Rq{sub eff}{sup 2}))l{sub i} which is a measure parameter for the ballooning stability, where q{sub eff} is the effective safety factor at the edge. The edge pressure gradient estimated by n-bar{sub e}{sup th} T{sub i} (95%)/(T{sub i} (95%){sup 0.5}/B{sub p} (a)) is proportional to (B{sub t}{sup 2}/(Rq{sub eff}{sup 2}))l{sub i} which allows us to understand that the ELMs are related to the ballooning instability. A time dependent analysis of the evolution of pressure and current profiles including the boot-strap current shows that the steep edge pressure gradient is close to the marginal value for the high-n ideal ballooning instability at the onset of ELMs. (author).
AU - Kamada, Yutaka
AU - Sato, Masayasu
AU - Kikuchi, Mitsuru
AU - Mori, Masahiro [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment]
KW - 70 PLASMA PHYSICS AND FUSION TECHNOLOGY
KW - JT-60U TOKAMAK
KW - EDGE LOCALIZED MODES
KW - H-MODE PLASMA CONFINEMENT
KW - BALLOONING INSTABILITY
KW - BOOTSTRAP CURRENT
KW - PLASMA RADIAL PROFILES
KW - BETA RATIO
KW - 700340
KW - PLASMA WAVES, OSCILLATIONS, AND INSTABILITIES
DO -
UR -
PB -
CY - Japan
PY - 1994
DA - 1994-08-01
LA - English
J2 -
C1 - Japan Atomic Energy Research Inst., Tokyo (Japan)
C2 -
ER -