Study of Integrated High-Performance Regimes with Impurity Injection in JT-60U Discharges

摘要

Injection of argon in ELMy H-mode discharges has enabled extension of these plasmas in JT-60U to high density with good confinement and high radiation loss power fraction. By operation of the outer divertor strike point on the divertor dome, confinement improvement, electron density n_e, and radiation-loss power fractions P_(rad) / P_(heat) close to the ITER requirements have been achieved simultaneously ( HH_(98(y,2)) ～ 1; n_e ～ 0.8 n_(GW), the Greenwald density limit; and P_(rad) / Pheat ～ 0.8). Linear microstability analyses show a region of reduced growth rate in the argon-seeded discharge for the ITG/TEM mode near r/a = 0.64; the ETG growth rate is greatly reduced across the entire profile and completely quenched around r/a = 0.5 - 0.7. The reduced growth rates are related to the impurity effects, the deuteron dilution, and the temperature gradients.