First wall of thermonuclear device

In future thermonuclear devices, it is expected that higher thermal loads than those at present are given constnatly for a long period of time to first walls. The first wall in accordance with this invention is intended to cope with this. Carbon fibers are oriented substantially in the direction of thickness, and carbon fiber-reinforced composite carbon materials having a ratio of heat conductivity in the direction of the thickness to that in the direction perpendicular to the thickness is not less than 2, and a heat conductivity in the direction of the thickness of not less than 3 W/cm.degC are used as the main material. The first wall is disposed with one side substantially in perpendicular to the direction of the thickness being faced to plasmas. As a result of various tests, it has been found that the first wall according to this invention can suppress the surface temperature, vapor pressure and sublimation loss even when it is exposed to high thermal load for a long period of time. (I.S.)