Vacuum ultraviolet radiometry with hydrogen arcs. 2: The high power arc as an absolute standard of spectral radiance from 124 nm to 360 nm.

A wall-stabilized hydrogen arc can be utilized as a standard source of spectral radiance since the continuumemission coefficient is calculable to within a few percent. Previous efforts to apply this concept have been impeded by relatively large uncertainties associated with the plasma diagnostics. The present approach yields absolute intensities independent of other radiometric standards or the accuracy of any plasma diagnostics. The hydrogen arc is operated at high temperatures where the continuum emission coefficient reaches a broad, unique, and calculable maximum. Comparisons with other primary standards are consistent with the estimated uncertainty in the arc continuum intensities.