[armor material] - one dimensional carbon composite - 5 cm x 5 cm x 1.9 cm thickness - saddle shape [cooling pipe] - 3 coolant lines - swirl tube

Fig. 2-15 A test piece of the divertor plate and its cross section A surface material is the one dimensional carbon composite of 5 cm x 5 cm in surface area, 1.9 cm in thickness. A substratum and cooling pipes are made of copper, 3 parallel coolant lines. There are a particular structure (swirl tube) inside the cooling pipe to enhance its efficiency.

Table 2-1

The achieved data and the ITER requirements for the divertor plate

A divertor plate installed in the divertor configuration which consists of the first wall of ITER should withstand a high, radiative heat flux. The surface is made of beryllium and/or carbon-composite, while the substratum is made of copper with cooling pipes. We need a metallurgical joining technique for thick materials of different nature, which will withstand cyclic heat loads. We have made a test piece composed of parallel multi-cooling pipes, one dimensional carbon composite, and copper substratum (Fig. 2-15). We have also made heat load tests by using an electron beam to irradiate the test piece. The results of tests are shown in Table 2-1 with the ITER requirements. All requirements are satisfied with the test piece. Many trials and a fully worked-out plan have been done, such as detailed characterizations of the thick carbon composite development of a brazing solder without silver, the swirl tube which has a helical structure in the cooling pipe to enhance cooling efficiency and so on. The 5 MW heat load on 1 m2 is equivalent to 500 W on 1 cm2. This heat load corresponds to the 50 times of the heat load by comparison with the heat conduction material used in electric-power plant using oil as fuel.

Reference M. Araki et al., A Study on Plasma Surface Material of ITER, Purazuma, Kaku Yugo Gakkai-Shi, 71(5), 384 (1995).

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