Measurements of Gaseous Hydrogen–Nitrogen Laser-Plasma

Abstract

This work communicates laser-plasma experiments in a gaseous mixture of hydrogen and nitrogen. Time-resolved spectroscopy measures the first four Balmer-series hydrogen lines together with selected neutral and ionized nitrogen lines. Optical breakdown plasma is generated in a 1:1 hydrogen:nitrogen mixture at ambient temperature and 0.27-atm pressure. Time-resolved spectroscopy records emitted radiation with spatial resolution along the slit height for the H α , H β , H γ , and H δ lines. For 13 selected time delays from 0.25 μ s to 3.25 μ s and 0.025 μ s gate-widths, micro-plasma diagnostics is evaluated. Of interest are the peak separation and width of H δ and width of H γ for electron densities in the range of 0.1 to 1.0 × 10 17 cm - 3 , and comparisons with H β and H α diagnostics. Integral inversions interrogate spatial distributions of the plasma expansion. Applications include laboratory and stellar astrophysics plasma diagnosis.

Temporally and Spatially Resolved Emission Spectroscopy of Hydrogen, Cyanide and Carbon in Laser-Induced Plasma

“…The determination of the temperature and mole fraction of CN and carbon line-width along the slit is topic of ongoing research. The variation is expected to be analogous to recent hydrogen-nitrogen laser-plasma work [33]. Recorded spectra at a time delay of 3.7 µs and at 1 mm show lower temperature [16] than that reported here for the 1.2 µs time delay.…”

“…The determination of the temperature and mole fraction of CN and carbon line-width along the slit is topic of ongoing research. The variation is expected to be analogous to recent hydrogen-nitrogen laser-plasma work [33]. Recorded spectra at a time delay of 3.7 µs and at 1 mm show lower temperature [16] than that reported here for the 1. modified Boltzmann plot method [31] is utilized in the recently published program [32] for the determination of the best-fit FWHM, Δλ, and temperature, T, from the entire spectrum.…”

Laser-Plasma and Self-Absorption Measurements with Applications to Analysis of Atomic and Molecular Stellar Astrophysics Spectra

“…Electron density measurements utilize full-width at half-maximum and for H β and H γ peak-separation. However, the H γ peak separation method is applied in analysis of experiments in 0.136-atm:0.136-atm H 2 :N 2 gas mixtures [22] that show electron densities in the range of 0.1-1 × 10 17 cm −3 for time delays longer than those for the 0.75-atm H 2 experiments addressed in this work. Figure 4 illustrates the line-to-continuum ratios and corresponding temperatures.…”