Operation of TEXTOR-94 with tungsten poloidal main limiters

In TEXTOR-93, experiments have been performed with the upper and lower polo idal limiter blocks made of vapour sprayed (VSP) tungsten (about 0.5 mm) de posited on graphite with a rhenium interlayer. A series of discharge condit ions have been performed (density scan, scan of the auxiliary heating power , radius scan). There has been found no restriction for operation at any de nsity with auxiliary heating. For Ohmic conditions the same density with te stlimiters could be reached. Under siliconized conditions no severe accumul ation of tungsten in the plasma centre could be detected. The blocks could in general stand surface temperatures below 1700 K. Most of them survived a lso temperatures above 3000 K without exfoliation. However, some blocks sho wed severe damage by melting or exfoliation probably due to insufficient co ntact of the tungsten layer with the graphite. (C) 2001 Elsevier Science B. V. All rights reserved.