摘要
In this article, we shall report the results of the spectroscopic measurements of the plasma parameters utilizing the spectral lines emitted from the air atoms surrounding plasma (O I line at 777.19 nm and N I at 746.83 nm). The plasma was created via irradiation of plane solid aluminum target in open air by a high peak power Nd: YAG laser pulses at fundamental wavelength of 1064 nm. The emission spectra were recorded using Echelle type spectrograph in conjunction with a time gated ICCD camera at different delay time from 1 to 5 μs and at a fixed gate time of 1 μs. The plasma electron density was measured utilizing the Stark broadening of the N I and O I lines and then compared to the reference density as deduced from the optically thin Hα-line at 656.27 nm appeared in the same emission spectra. The results show that under our experimental conditions the air lines are subjected to moderate absorption. The plasma electron temperature was measured utilizing the relative spectral intensity of the air (O I to N I) lines after correcting their spectral radiance against absorption. The standard temperature was measured utilizing the Al II ionic lines. A comparison to the reference temperatures shows a very close agreement after correcting the emission spectral radiance of the air lines against self absorption, which emphasizes the importance of correction process.
In this article, we shall report the results of the spectroscopic measurements of the plasma parameters utilizing the spectral lines emitted from the air atoms surrounding plasma (O I line at 777.19 nm and N I at 746.83 nm). The plasma was created via irradiation of plane solid aluminum target in open air by a high peak power Nd: YAG laser pulses at fundamental wavelength of 1064 nm. The emission spectra were recorded using Echelle type spectrograph in conjunction with a time gated ICCD camera at different delay time from 1 to 5 μs and at a fixed gate time of 1 μs. The plasma electron density was measured utilizing the Stark broadening of the N I and O I lines and then compared to the reference density as deduced from the optically thin Hα-line at 656.27 nm appeared in the same emission spectra. The results show that under our experimental conditions the air lines are subjected to moderate absorption. The plasma electron temperature was measured utilizing the relative spectral intensity of the air (O I to N I) lines after correcting their spectral radiance against absorption. The standard temperature was measured utilizing the Al II ionic lines. A comparison to the reference temperatures shows a very close agreement after correcting the emission spectral radiance of the air lines against self absorption, which emphasizes the importance of correction process.
