Features and advantages of boron carbide as a protective coating of the tokamak first wall

The physical aspects of graphites, carbon-fibre composites (CFC) and boron–carbon coatings as plasma-facing materials are considered. The advantages and disadvantages of their applications in tokamaks are analysed. A crystalline boron carbide coating is shown to have excellent erosion characteristics, low hydrogen retention capacity and high resistance under high-energy loads; these properties of boron carbide differ significantly from those of graphite. In modern fusion devices, crystalline boron carbide deposited on graphites with a high thermal conductivity can be used successfully as a plasma-facing material. A new technique suitable for deposition of boron carbide coating in the plasmas of modern tokamaks is described. It is concluded that a thick renewable boron carbide coating can be used successfully under the conditions of the first wall of the International Thermonuclear Experimental Reactor.