Thermo-Hydraulic Performance And High Power Transmission Characteristics Of The RS Torus Window Prototype

High power CVD-diamond torus windows being the 1 st tritium barrier of the ECRH upper port launcher should be able to provide continues transmission of 2 MW power beam at 170 GHz. Heating of the window due to power absorption in CVD diamond disk of about 0.1% of total power induces thermal (secondary) stresses. Moreover the mm-wave optic of the remotely steering (RS) launcher requires off-centre propagation of the beam through the window. Steering angle of 12° corresponds to about 27 mm off-centre shift of the beam spot, which in turn leads to the asymmetrical heating of the window provoking additional stresses and potential occurrence of plastic deformation of the window cuffs. Finite element analysis of the different cooling concepts allowed choosing direct edge cooling of the diamond disk as the only one which fulfils cooling efficiency requirements. For high power and thermo-hydraulic tests the torus window prototype based on a large area CVD diamond disk (∅ 106 mm) was manufactured at FZK. Results of the tests are reported below.