APPLICATION OF PYROLYTIC BORON-NITRIDE IN FUSION DEVICES

Armor made of low-Z materials with low sputtering yields is widely used in fusion devices to protect the first wall. The use of pyrolytic boron nitride (PEN) as an armor material for the first wall and screens for additional heating systems in fusion devices is discussed. PBN possesses some potential advantages over other ceramics at high temperatures, for example, its mechanical strength, electrical resistance, heat conductivity, dielectrical properties and resistance to neutron damage are better than many other ceramics. An investigation of the change in physical and structural properties of the PBN surface, irradiated with those ions which prevail in the tokamak plasma as impurities, was carried out (C+, Fe+, W+ and others). The PBN was irradiated by high current electron beams, γ-quanta was analyzed using IR Adsorption Reflection Spectroscopy and Secondary Ion Mass Spectroscopy; the surface resistance was also measured. It was shown that PBN properties are recovered after annealing at 1300 K. © 1990.