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(EX/P2-04) Enhanced Pedestal Pressure and Parameter-linkages Determining Edge Pedestal Structure in JT-60U Type I and Type II ELMy H-mode

Y. Kamada¹⁾, H. Takenaga¹⁾, H. Urano²⁾, T. Takizuka¹⁾, T. Hatae¹⁾, Y. Miura^1)
 
1) Japan Atomic Energy Research Institute, Naka-machi, Japan
²⁾ Max-Planck-Institut fur Plasmaphysik, Garching, Germany

Abstract.  In JT-60U, with the extended capability of high triangularity operation, multiple pellet injection and high power heating including the negative ion based NBs, we have newly clarified the parameter-linkages determining the pedestal structure (i.e. 'width' $\sim$ ion poloidal gyro radius (not depends on $\beta_{p}^{}$-ped), and 'gradient' (alpha parameter) is almost constant at low triangulariy, while the alpha increases linearly with $\beta_{p}^{}$-total at high triangularity). As a result, we have enhanced the pedestal pressure of the ELMy H-mode by factors of 2-2.5 at the same plasma current and plasma shape, and extended the high confinement regime to a high density. We found that the pedestal stored energy Wped increases with the core energy (or $\beta_{p}^{}$-core) at high triangularity (>0.3-0.4), while W_ped is low and almost constant independent of heating power at low triangularity (<0.2). This observation gives a new direction for the scaling study of Wped. In addition, we have expanded the type II (grassy) ELMy high confinement regime (with a small heat load on to divertor plates) to the low-q ( q₉₅ < 4) regime, and demonstrated successful compatibility of the type II ELMs with the pellet injection.

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