HIGH-CURRENT HOLLOW-CATHODE SOURCE AS A RADIANT INTENSITY STANDARD INTHE 40-125-NM WAVELENGTH RANGE

The radiant intensity of VUV emission lines of a high-current hollow-c athode source has been determined for the 40-125-nm spectral range. Th e source is operated at a constant current of 1 A with an aluminum cat hode. Different rare gases are alternatively used as the buffer gas at pressures of similar to 100 Pa. The radiant intensity has been determ ined by comparison with the calculable spectral radiant flux of the el ectron storage ring BESSY. Radiant intensities of the emission lines a re in the 7-1400-mu W/sr range. The long-term reproducibility of the r adiant intensity of the source is within +/-10% (2 sigma value). The s ystematic uncertainty of the radiometric calibration is better than 9% (root 3 sigma value).