In the regime of Improved Ohmic Confinement (IOC) in ASDEX the energy confinement time tau E increases linearly with increasing line-averaged density ne up to the density limit. The establishment of the IOC is accompanied by a substantial reduction of the external gas feed, concomitant with large decreases of all plasma edge fluxes. However, the data do not supply conclusive evidence that the IOC is primarily connected with the recycling conditions. More recent observations with very clean machine conditions seem to indicate that the impurity radiation plays a significant role.
Characterizing the edge plasma of different Ohmic confinement regimes in ASDEX