MISTRAL campaign in support of W7-X long pulse operation

Following two initial campaigns [1], Stellarator Wendelstein 7-X (W7-X) has now completed the construction phase by installation of active cooling all plasma facing components. The machine is presently commissioned for next campaign (OP2) aiming at 1 GJ per pulse, e.g. 100 s 10 MW, eventually 18 GJ, 1800 MW. key heating system Electron Cyclotron Resonance Heating (ECRH) system, consisting gyrotrons with power gyrotron ranging from 0.6 MW up to 1.0 140 GHz. A phased upgrade in progress addition 2 and development 1.5 2.0 gyrotrons, such that end 4 will be available each class 1.0, [2]. increased ECRH power, combined O2 X3 schemes high densities, lead microwave stray radiation. This non-absorbed diffuses inside vessel incident on in-vessel components including vacuum windows attached diagnostic systems. fraction radiation absorbed resistive or dielectric losses these components, leading thermal loads scale levels pulse length. At W7-X a launch facility ’MISTRAL’ used qualify invessel use specified surface densities [Wm −2 ]. paper reports MISTRAL 2020 2021 testing during OP2 W7-X, as well an EUROfusion program assessing ITER dedicated, absolutely calibrated, caloric load was developed obtain measurement conveniently expose samples. Amongst other we report shielding concepts using metal enclosures absorbing coatings windows.