IN-SITU DEPOSITION OF SILICON ON THE LEADING-EDGE OF THE ALT-II LIMITER IN TEXTOR-94

Silane gas was injected through apertures in the leading edges of the ALT-II limiter in TEXTOR during tokamak discharges. The gas injection produces a hard, robust local coating which protects the exposed surfa ces against erosion. As a byproduct, metallic impurities in the plasma are reduced, a radiation belt at the plasma periphery is generated an d there is evidence that a major part of the wall is coated, For the g iven experimental condition the rise time until the carbon flux on a s iliconized surface reaches the former level amounts to 5-10 s for ohmi c discharges. For strongly heated discharges the deposited Si layer is eroded in about 1 s. The deposition technique has potential applicati ons for in-situ protection/repair of divertor erosion in ITER.