Characterization of the hydrogen emission in divertor II of ASDEX-Upgrade

Detailed experiments have been carried out in ASDEX-Upgrade to characterize detached plasma conditions in divertor IT. This paper presents measurement s of the hydrogen emission in the visible and VUV spectral range that disti nguishes between the ionization front and the recombining divertor plasma. Plasma parameters in the recombination dominated region were obtained from the Balmer continuum and line emission. By means of the ADAS programme pack age the rate of volume recombination is evaluated including the effect of o pacity. The optical thickness was experimentally determined from the line r atio of L-beta and H-alpha. In the recombining plasma we have observed an i nverse response of PI, light during the spatial broadening of ELMs. Inverse ELMs show signatures of convective transport. (C) 1999 Elsevier Science B. V. All rights reserved.