Concept Of The Bolometry Diagnostics Design For Compass-Upgrade

The COMPASS-Upgrade tokamak, being designed as a medium-sized tokamak, operating with a hot first wall, allows for the study of DEMO-relevant plasma exhaust physics, crucial for future reactors. Bolometry diagnostics for COMPASS-U, consisting of metal foil bolometers and AXUV diodes, are proposed to measure spatially-and time-resolved radiation losses. Metal foil bolometers supply the absolute value of radiation power, whereas the AXUV diodes can observe fast phenomena such as MHD activity. Coverage of the whole poloidal cross-section by bolometers' cameras allows tomography reconstruction of the local plasma emissivity. The metallic foil bol-ometry system will be based on sensors with a gold absorber on a silicon nitride substrate with a platinum resistor. Special modifications, e.g., channel separation, will be applied to the detectors to fulfil the requirements. Due to the high temperature, effective thermal shielding and cooling are essential to reduce the risk of damage to the detectors as well as reducing noise in the measured signal. The pin-hole cameras spatial configuration was optimized to provide the best performance under the given engineering constraints. The position of the cameras strongly depends on the space available behind the plasma-facing components (PFC). The proposed layout allows for an efficient observation of the confined plasma as well as that of the divertor region.