Ultraviolet/vacuum-ultraviolet emission from a high power magnetron sputtering plasma with an aluminum target

We report the in situ measurement of the ultraviolet/vacuum-ultraviolet (UV/VUV) emission from a plasma produced by high power impulse magnetron sputtering with aluminum target, using argon as background gas. The UV/VUV detection system is based upon the quantification of the re-emitted fluorescence from a sodium salicylate layer that is placed in a housing inside the vacuum chamber, at 11?cm from the center of the cathode. The detector is equipped with filters that allow for differentiating various spectral regions, and with a front collimating tube that provides a spatial resolution?????0.5?cm. Using various views of the plasma, the measured absolutely calibrated photon rates enable to calculate emissivities and irradiances based on a model of the ionization region. We present results that demonstrate that Al+ ions are responsible for most of the VUV irradiance. We also discuss the photoelectric emission due to irradiances on the target produced by high energy photons from resonance lines of Ar+.