Fluid Targets for Heat Removal in Fusion Reactors

Fluid targets, i.e. liquids or solids moving through the high heat flux zones, may be a way to solve the heat exhaust and erosion problems in fusion reactors. Some of the ideas are not new and are presented in the literature in widely scattered articles. Unfortunately, the discussion is often not detailed enough to judge their applicability. They have e.g. been addressed in the framewerk of the INTOR and ITER studies. This report contains contributions of members of a study group constituted from scientists and engineers of different Institutes of KFA end of 1993. The group met a few times to discuss ideas and problems associated with the use of fluid targets for heat exhaust in fusion reactors. The starting point has been a proposal for a respective program on TEXTOR. The main aim of the group's work has been so far to identify critical questions warranting in depth studies in preparation of a potential experiment in TEXTOR. The treatment of the matter in these contributions is by now means complete and exhaustive but some important conclusions still can be drawn. Reference to literature is made in the individual contributions where appropriate. In addition to these references a number of publications of general interest have been used and are listed in the appendix. The contributions partly consist of summaries in english and copies of figures and viewgraphs in german which are selfexplaining in most cases

Enhanced small scale turbulence oscillations correlated to sawtooth relaxations in the textor tokamak

A periodic enhancement of the microturbulence level by sawtooth relaxations has been detected by CO$_{2}$ laser forward scattering in the TEXTOR tokamak. This feature is reproduced quantitatively by a heat transport code in which the anomalous electron transport coefficient is calculated self consistently following a theoretical model of the saturation of the dissipative trapped electron instability. The code also predicts a strong modulation of the heat whole plasma and a strong "profile consistency" as continuous temperature measurements have interpretation of these results is given. Calculated global plasma parameters, such as the energy confinement time and the loop voltage, are in good agreement with the measured values