The physics governing the height of the X-point radiator (XPR) and the influence of the related radiation losses on the edge temperature profiles is studied with a reduced power balance model, which is an extension of a model developed to study XPR access. For ASDEX Upgrade parameters with a heating power of 10 MW, the model reproduces that the X-point radiator can be moved from the X-point up to 14 cm into the confined plasma, dissipating up to 70% of the heating power. The key parameter is the neutral density in the X-point region. A reduction of the edge kinetic pressure gradient of about 50% is found which could explain the suppression of edge localized modes observed in experiment. The calculated edge temperature response is consistent with experimental data.
This paper investigates the physics behind the height of the X-point radiator (XPR) and how the resulting radiation losses affect the edge temperature profiles of the plasma. The model shows that the XPR can be moved up to 14 cm into the confined plasma, dissipating up to 70% of the heating power, with the key parameter being the neutral density in the X-point region. The edge temperature response is consistent with experimental data, and the reduction in edge kinetic pressure gradient could explain the suppression of edge localized modes observed in experiments.