Wall-stabilized arc-plasma source for radiometric applications in the range 200 nm to 10 μm

Based on experience acquired over many years in operating high-power, stationary are plasmas for quantitative spectroscopy, the Physikalisch-Technische Bundesanstalt (PTB) has begun to investigate the suitability of argon are-plasma radiation fur radiometry. We have demonstrated, through the design and operational control of the are source, that fur example argon plasma generated at 150 A and a pressure of 200 kPa provides radiation with a stability of about 10(-3). We also state a long-term reproducibility of better than 5 x 10(-3) because all operational and geometrical parameters affecting the plasma radiation can be controlled with a relative uncertainty of at least 10(-3). The radiation propel-ties have been investigated and carefully characterized in the wavelength range 250 nm to 10 mum at the new PTB detector-calibration facility.