Absolute radiometric calibration of a VUV spectrometer in the wavelength range 46–300 nm

Vacuum ultraviolet (VUV) radiation corresponds to photon energies exceeding 6.2 eV and provides access atomic molecular resonant transitions in various plasmas. Determining population densities of electronic levels directly connected the ground state requires an absolute intensity calibration VUV spectrometer. For this purpose, synchrotron from electron storage rings is typical primary standard source associated with transport effort operating costs. Alternatively, a complex procedure using several secondary standards discharges at setup use can be applied. In work, avoiding cover wavelength range 46–300 nm accessible two detectors—a photomultiplier tube channel multiplier—is presented. A combination different sources—two deuterium arc lamps, branching-ratios nitrogen plasma high current hollow cathode—is applied for relative calibration. The based on simultaneous measurements lines low pressure helium discharge spectrometer absolutely calibrated optical emission Special focus laid uncertainties depending range. applicability demonstrated hydrogen 80–300 nm. Using emissivity Lyman series, first six excited states are calculated considering opacity effects. excellent agreement results Balmer series by spectroscopy manifests validity performed