Biberman ‘free–bound’ continuum correction factor approximation for line-to-continuum temperature diagnostic of aluminium laser plasma

Abstract

The applicability and versatility of plasma diagnostics to various fields is constrained by numerous challenges. Spectroscopic coefficients are crucial for successful implementation of a particular diagnostic technique. The 'line-to-continuum' technique, which is used to determine the electron temperature (T e ), is applicable to a large range of wavelengths and spatio-temporal coordinates within a laser plasma plume via emission spectroscopy. To successfully utilize this technique, a number of spectroscopic coefficients are required. The Biberman 'free-bound' continuum correction factor (ξ fb ) is a required constant for the line-to-continuum technique which displays a strong temperature and wavelength dependence for λ < 450 nm. Approximation of ξ fb over a discrete temperature range for aluminium is achieved using space-and time-resolved visible emission spectroscopy in the optical range (λ = 350-470 nm). Complementary temperature diagnostics are undertaken to determine the excitation temperature (T exc ) and the ionization temperature (T ionz ). Convergence in the calculated T exc and T ionz spatial profiles is identified as regions of local thermal equilibrium. Calculated average temperatures (T avg ) over the range T ∼ 20-34 × 10 3 K are determined and used to approximate values for the Biberman 'free-bound' continuum correction factor for Al III (453 nm) and elucidate its temperature dependence.

On the growth mechanism of nanoparticles in plasma during pulsed laser ablation in liquids

“…where C is a constant taken from [23] and x is taken from [24] for the free-bound transitions. The use of this equation to calculate electron density from the plasma continuum radiation must be subjected to some experimental requirements.…”

Study of the Effect of Water Pressure on Plasma and Cavitation Bubble Induced by Pulsed Laser Ablation in Liquid of Silver and Missed Variations of Observable Nanoparticle Features

“…where n e and n i are the electron and ion densities, respectively, x and G are the Biberman and the Gaunt [45] factors, and m is the electron mass. The Biberman and the Gaunt factors are connected with the free-bound or recombination continuum Table 1.…”

Influence of plasma density on the cross sections of radiative recombination to configuration-averaged excited nitrogen and oxygen atoms and ions

“…Consequently, the plasma emits radiations, so the most widespread diagnostic used to analyze the plasma is emission spectrometry [17,18] due to its versatile and non-intrusive character [19]. Depending on the calibration procedure, many quantitative informations may be inferred from the measured spectra: electron density [20], density of the excited states involved in the observed transitions [21,22] and temperature [23,24]. These data may be useful to validate collisional-radiative models [25][26][27] which provide a precise and quantitative description of the mechanisms governing plasma chemistry.…”