Measurement of hydrogen transport functions by means of precision arc experiments

Abstract

Motivated by discrepancies of measured and calculated hydrogen transport coefficients, pure hydrogen arc plasmas have been investigated again in the wide temperature range from 5000 to 27,000 K. The plasmas are generated in cascaded arc chambers with 2, 3, and 5 mm channel diam. Temperature diagnostics are performed by side-on spectroscopy in the Balmer region, using an automatic data acquisition system and computer processing. The immediate results are in excellent agreement with precision measurements by other authors. The electricalE—I characteristics are recorded using cascade plates as probes. These characteristics and the temperature measurements together yield the transport coefficients as a function ofT. The present results for the electrical conductivity are in very good agreement with theory. As for the heat conductivity, some improvements could be achieved in the relative dependence, but the experimental values are still above the theoretical ones. In the region of low ionization this discrepancy is explained by deviations from LTE in the arc plasma. Here, a rigid PLTE analysis is presented.