Thermal processes in tokamaks of the next generation and future reactors

In future tokamaks heating power will increase considerably compared with present-day machines. This leads to increased heat loads to surfaces exposed to the plasma. In this paper the models used to calculate the limits for thermal flux imposed by maximum permissible surface temperature and maximum permissible stress are reviewed. Additional constraints for the design resulting from damage caused by disruptions and from erosion by the plasma are mentioned. Different methods of laboratory testing of small samples are surveyed. The designs of the limiters of the next generation of tokamaks are compared. (orig.)