Numerical analysis of a toroidal rotation effect on the type-I ELM in JT-60U

Effect of a toroidal rotation on the type-I edge localized mode in JT-60U is investigated numerically. As the result of the numerical analysis, it is confirmed that the plasma rotating experimentally in the co-direction to the plasma current is approximately on the stability boundary of the MHD mode even when the rotation is neglected. However, the plasma rotating in the counter-direction is far from the stability boundary under the static assumption. Since both plasmas have the type-I ELM, the edgeMHD stability is reassessed with the toroidal rotation effect. This stability analysis clarifies that the rotation of this counter rotating plasma can destabilize the edge localized MHD mode, and can resolve the discrepancy that the type-I ELM is observed in the plasma that is MHD-stable under the static assumption.