{'fraction_non_alphanumeric': 0.03361344537815126, 'fraction_numerical': 0.012281835811247576, 'mean_word_length': 5.7894736842105265, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Biberman ‘free–bound’ continuum correction factor approximation for line-to-continuum temperature diagnostic of aluminium laser plasma

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 (Te), 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 (ξfb) is a required constant for the line-to-continuum technique which displays a strong temperature and wavelength dependence for λ < 450 nm. Approximation of ξfb 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 (Texc) and the ionization temperature (Tionz). Convergence in the calculated Texc and Tionz spatial profiles is identified as regions of local thermal equilibrium. Calculated average temperatures (Tavg) over the range T ∼ 20–34 × 103 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.