Spectroscopic Study of Recombination Continuum in Arc-Heated ColdExpanding Plasma Jet

摘要

We generate cold recombining hydrogen and helium plasmas with low electron density, andanalyze recombination radiation by optical emission spectroscopic measurement. We measuretheir electron temperature and density from the continuum spectra as well as from the lineintensities of LTE levels. The existing theory of spectral intensity of the recombination continuumexplains the observed continuum spectra very well even for very low electron temperature region,Te ≤0.2 Ev. The electron temperature and density determined from the continuum spectra agreewith those from the line intensities within 10 - 20 % error. We confirm that unresolved lines ofradiation from very highly excited levels are smoothly connected to the continuum spectra.