On the influence of the condensed particles on the absorption properties of plasma created by ablation controlled arc in a capillary

Abstract

The results of experimental studies of the absorption properties of plasma created by ablation controlled arc in a capillary are presented. It is shown that the dominant influence on the plasma absorption properties is exerted by condensed particles formed in relatively low-temperature zones in the vicinity of the capillary wall and on the periphery of the plasma jet, whereas the plasma bremsstrahlung is optically thin. The nonmonotonic behavior of the plasma optical thickness in the spectral range Δλ=400−700 nm, as well as amplification of the probing radiation in a relatively narrow wavelength interval Δλ=628±5 nm, caused, probably, by resonant excitation of condensed particles by electromagnetic radiation, are detected. The estimations of the condensed particles parameters (the average size dD≈2−4 nm, the concentration ND=(1−5)·1013 cm−3, the volume fraction fV≈(0.1−3)·10−6), which quantitatively consistent with the results of studies of the microstructure of the condensed phase on scanning electron microscope, have been obtained.