Quasistationary High Confinement Discharges with trans-Greenwald Density on TEXTOR-94

Confinement quality as good as ELM-free H-mode at densities substantially above the Greenwald density limit ( n̄e,0/nGW0ex0ex=0ex0ex1.4) has been obtained in discharges with a radiative boundary under quasistationary conditions for 20 times the energy confinement time. This is achieved by optimizing the gas-fueling rate of RI-mode discharges which tailors their favorable energy confinement and leads to discharges with beta values just below the operational limit βₙ0ex0ex=0ex0ex2 of TEXTOR-94, thereby effectively avoiding confinement back transitions or disruptions. In addition, this high-density regime is favorable for helium removal and results in figures of merit τp,He*/τE≈10--15, relevant for a future fusion power reactor.