Spectroscopic diagnostics of laser-induced aluminum and indium plasma under conditions of moderate power of stimulation of obstacle

The paper deals with the investigation of the radiation of an erosion plasma formed as a result of interaction between laser radiation with a duration of $20$ ns, intensity of $(3-5)\times10^8$ W/cm$^2$, and wavelength of $1.06\mu$m and aluminum and indium obstacles. The photoelectric technique is used to record radiation spectra from different spatial zones of the laser jet in the range from $210$ to $600$ nm. The dynamics of laser jet radiation on individual transitions of aluminum and indium atoms and ions are investigated, as well as the distribution of effective radiation fluxes from different excited levels of aluminum and indium atoms. It is demonstrated that excited $\mathrm{Al}$ and $\mathrm{In}$ atoms and InII ions are formed in this plasma. The dielectronic recombination reaction in the plasma core of the laser jet proceeds over the course of $\tau_{\text{rec}}\le800$ ns $(\mathrm{AlII})$, 25 ns $(\mathrm{InIII})$, and $180$ to $360$ ns $(\mathrm{InII})$. The average propagation velocity of the laser jet is $6$ to $8$ km/s. The obtained results are of interest from the standpoint of performing optical diagnostics of laser-induced plasma of aluminum- and indium-containing crystals, as well as for comparison with the results of numerical simulation of the characteristics of laser-induced plasma on the basis of metals of group $\mathrm{III}$.