From photon-counting measurements to radiated power density estimates at WEST

Multi-energy soft and hard x-ray pinhole cameras have been designed, built and operated at the WEST tokamak to measure the plasma emission in multiple energy ranges and infer profiles of impurity densities, electron temperatures, as well as non-Maxwellian tails, including runaway electrons. This novel imaging diagnostic technique combines the best features from both PHA and multi-foil methods employing a PILATUS3 x-ray detector in which the lower energy threshold for photon detection can be adjusted independently on each sensor of their 10$^5$ to 10$^7$ pixelated systems. Described in this presentation is a new methodology to estimate also the local radiated power density profiles from photon-counting measurements in several energy bands, which could become particularly useful for machines cladded with metal plasma facing components (PFCs). This novel application is possible since the pixel responsivity is well characterized by a complementary error function while the multi-energy measurements between adjacent energy-levels is described well by a Probability Density Function of a Gaussian distribution. This methodology is being develop at the WEST tokamak for long-pulse-plasmas up to 360 s aiming for a real-time measurement capability up to 1000s for the 2024-C10 campaign.