Lifetime predictions for ceramic windows in fusion reactors

The electron cyclotron resonance heating is considered as an external plasma heat source for fusion reactor systems. The window which separates the reactor vacuum from the electron tube vacuum, is heated up due to dielectric losses. The temperature gradients in the window cause thermal stresses and, especially in case of ceramic windows, the tensile stresses are the basis of lifetime evaluations in different candidate materials. This contribution presents the results of calculations of the temperature and the stress distribution in a gyrotron window. Due to the radial distribution of the electric power, temperature gradients develop in the radial direction which lead to tensile tangential stresses. Two candidate materials, Al2O3 and AlN have been considered. (H.W.). 6 refs.; 5 figs.; 3 tabs