High-power ergodic divertor operation of Tore Supra

The improved ergodic divertor, with a power handling capability of 9 MW over 30 s, opens the way to steady-state operation. Bootstrap current generation is investigated with fast wave electron heating and beta(p) similar to 0.3 is achieved with P-add similar to 7.6 MW. Lower hybrid current drive up to 75% of the total current of 1.3 MA has been achieved with P-LH similar to 4.5 MW. Detachment in this open divertor configuration occurs at 44% of the Greenwald density in ohmic shots. Target-plate plasma temperatures drop below 10 eV at detachment and then reach 8 +/- 1.75 eV. The energy flux to the target plate measured by IR and Langmuir probe vanishes in this detached regime. Enhancement of radiation H-Rad, With respect to the JET scaling, is achieved for some ED shots, H-Rad similar to 5. Self-healing of the confinement loss in the boundary layer is numerically investigated. In qualitative agreement with experimental results, an intrinsic transport barrier is found to build up in the vicinity of the separatrix.