Proposal of a testing procedure to qualify ITER window assemblies and absorbing coatings exposed to high microwave stray radiation

•In Tokamaks, window assemblies are essential to preserve operation conditions.•In ITER, the materials will be exposed to harsh environment in presence of tritium.•An important hazard to the windows is the microwave radiation.•The main degradation causes of windows under microwave loads have been identified.•A series of laboratory tests have been defined, to qualify the materials.