Development of Diagnostic Methods for Seeded Air and Nitrogen Plasmas

摘要

Absolute emission coefficients of nitrogen atomic lines, of a wavelength increment of the N2(+)(1-)(0, 0) band system, of the electron continuum and of several atomic lines of the seed material were measured in atmospheric pressure nitrogen and air plasma jets seeded with K2CO3 powder. Radial temperature distributions determined from measured emission coefficients were compared as the mean temperature of the plasma was reduced from 6000K to 3000K. In the lower range, which is most characteristic of the seeded air accelerator, temperatures determined from both absolute and relative intensities of atomic lines of the seed material agree well with those obtained from the electron continuum. The best species of radiation for temperature measurements in the range of 2500K to 4000K was, as the result of the investigation, selected to be the continuous radiation emitted by the seed material itself. Errors in temperatures determined from the measured continuum and resulting from averaged variations in seed concentration and its uniformity of distribution are shown to be less than 5% in the lower temperature range. (Author)