ИСТИНА

Varying the properties of laser-induced plasma we can try to imitate the emission of various objects in atmosphere (meteor wake, airglow) and in outer space in different atmosphere and pressure. We focused on emission of “hard” molecules like orange bands of FeO and CaO , which spectra cannot be calculated theoretically due to complex structure of electronic state. Thus we vary conditions to make spectra profiles as close as possible to the ones observed during the Benešov bolide event. It allows reconstructing the composition and behaviour of meteor wake We measured emission spectra of atomic Fe,Ca and their monoxide varying delay after laser pulse and ambient pressure from 0.16 Torr to atmospheric. Plasma temperature and electron number density were calculated where possible. By comparison of experimental spectra and spectra of Benešov bolide at different heights we showed that the emitting bolide wake is formed under 7-10 times higher pressure than the one at the corresponding altitude. The obtained data lead us to suggestion that the CaO in plasma forms from oxygen from atmosphere primarily, while FeO – from target material. We have also performed plasma diagnostics using atomic emission by construction Boltzmann and SahaBoltzmann plot and fitting synthetic spectra of CaO red system to experimental spectra obtained in laser-induced plasma. It was found that the excitation (atomic species), vibrational and rotational temperatures of the experimental spectra indicate the absence of local thermodynamic equilibrium (LTE) and does not coincide match with each other under lower pressure. The atomic excitation temperature are is close to 10000 K, vibrational temperature varies in the range of 3500–5000 K, while the rotational temperature is noticeably lower than ~2000–3000 K. Moreover, the specific values of rotational temperatures grow rotational quantum number. We can conclude that the high energy levels are overpopulated and the possible reason is that the high translational energy results in excitation of high energy states, but complete thermolization is not possible due low collision rate.