Behaviour of boron- and titanium-doped graphite limiters under high heat loads in TEXTOR
Boron-doped graphite (3.5 % B and 20 % B in C) and titanium-doped graphite (2.1 % Ti in C) have been tested in TEXTOR as a single main limiter for typically 20-40 discharges. Convective power loads up to about 30 MW/m2 led to maximum surface temperatures between 2400-2800 C. Severe cracking occurred on the 20 % boron-doped graphite material showing that it is not applicable as plasma facing material under high heat loads. Some large cracks have also been observed on the RGTi limiter, probably caused by the strong anisotropy of the material. The 3.5 % boron-doped material shows similar thermomechanical properties to a fine-grain graphite. Large thermal sublimation of boron and titanium has been observed starting at surface temperatures of about 2000 C and 1800 C, respectively. Very thick layers of redeposited boron or titanium were formed near the areas of high sublimation. Besides the doping species (boron, titanium) these materials sublime various (metallic) impurities at elevated temperatures.
Bibliographic Reference: Article: Journal of Nuclear Materials, Vols. 212-215 (1994) pp. 1189-1194
Record Number: 199411562 / Last updated on: 1995-01-10
Original language: en
Available languages: en