The toroidal containment of a fusion reactor includes ceramic windows for the admittance of exciting and stabilising microwave radiation to the plasma. These are critical components which see high temperatures and rapid thermal transients.
This exercise was intended to compare candidate materials and to assess alternative methods of fixing the windows. The work package included thermal modelling of the windows, using finite difference techniques and addressing two possible spatial power distributions, followed by algebraic stress analysis.
The candidate materials were ranked according to their resistance to fracture and to melting, under the conditions studied, and the effect of operating temperature on materials performance was quantified. The effect of fixing restraints was also determined and the optimum fixing method was identified. Unexpectedly, but obviously in retrospect, it was demonstrated that surface cooling of the windows with liquid nitrogen would increase the range of materials that could be used, thus reducing cost and improving reliability.