ИСТИНА

Meteoroids composition estimation generally relies on the analysis of meteor emission spectra observed during meteor events. These data are also used to study meteor ablation process, including investigation of ionization efficiency and luminous efficiency. Laboratory experiments with ablation of meteoric analogues with known composition can be used to model the ablation behaviour and emission spectra of real meteors. It is especially important for molecular emission of FeO and CaO, that cannot be theoretically described due to complex structure of electronic state. Laser-induced plasma is a universal plasma source for spectral diagnostics of processes under extreme conditions. Since plasma parameters, ambient atmosphere, pressure, and compositions of the ablated target can be easily varied in laboratory experiment, this source is ideal for laboratory modelling of meteor plasma. Research interest in combustion processes during the meteor events in the Earth’s atmosphere led us to study the process of CaO formation in plasma. Spatially resolved measurements are needed for this purpose and laser-induced fluorescence seems to be the most appropriate tool for such a study. Observation of CaO/Ca emission at different delays under low pressure lead us to suggestion that the formation of CaO in plasma occurs primarily using oxygen from ambient atmosphere. Therefore, abundance of CaO should have a strong dependency on the pressure of the surrounding media. Also, we performed plasma elemental imaging (resolution of 200µm along each of 2 axes) by the means of Ca and CaO fluorescence in laser plasma. We suggested and experimentally proved that Ca atomic lines Ca I 428.30 nm and Ca I 430.52 nm and bands of CaO blue system (B1Π → X1Σ) can be used for this purpose. The estimated spatial distribution of Ca atoms and CaO molecules in laser plasma proves our suggestion that CaO is formed both in laser plasma and in the meteor wake primarily using oxygen from ambient air on the periphery of the cloud and this process almost does not involve oxygen from the ablated material (CaCO3). This work was supported by the Russian Science Foundation (grant 18-13-00269-Π).