A GEM-based high-rate x-rays diagnostic for flux measurement during high voltage conditioning in vacuum insulated systems

The High Voltage Padova Test Facilities (HVPTF) is a R&D project focused on understanding the physical processes behind breakdown and micro-discharges in high-voltage insulation, as well as developing new diagnostics, models, and operational modes to address these challenges and aid in the stable operation of MITICA. The X-rays produced during breakdown have a spectrum that extends from low energy (~ keV) up to several hundreds of keV and a flux that can reach 106 photons/cm2s. This paper shows the development and preliminary results of a newly designed X-Ray diagnostic based on Gas Electron Multiplier (SXR-GEM). This detector is able to stand very high rate (> MHz) in single photon counting mode and can cover the energy range from 3-50 keV. The XR-GEM detector is equipped with anodic pads (256 pads 6x6 mm2) readout with a new data acquisition system called GEMINI, which gives the possibility to obtain a counting rate of several MHz and sub-ms time resolution together with mm spatial resolution. Preliminary measurement shows that this kind of diagnostic is able to reconstruct the time evolution of the discharge at very high rates and to provide X-rays imaging.