The paper investigates the improvement of methods for computing the concentration of nanoparticles in transparent liquids under the action of laser radiation. The exact solution of the third boundary value problem for the Einstein–Fokker–Planck equation is analyzed, the direct use of which in the Maple computer algebra system leads to computational instabilities at large values of the transfer parameter. A solution to the problem of unstable numerical calculations at high values of dimensionless parameters, leading to significant distortions of the result, is presented. The key result is to expand the working range of the transfer parameter and ensure the correct asymptotic behavior of the solution. Numerical experiments have confirmed the effectiveness of the proposed approach, which makes it a valuable tool for modeling and optimizing the processes of laser separation of nanoparticles.
Keywords: nanosuspension, laser radiation, concentration of nanoparticles, continuity equation, third boundary value problem, computer calculations, Maple
The spatio-temporal dynamics of plasma parameters was numerically investigated, and the radiation parameters were calculated for a strontium vapor laser (λ=430.5 nm SrII) under optimal conditions of active medium pumping, which we found experimentally. The analysis of the obtained results showed that under the conditions of excitation of a pulse-periodic discharge in the active element, which provide the maximum pumping rate of SrII levels due to impact-radiation recombination, a sufficiently high degree of spatial homogeneity of plasma in the active medium is realized, which is necessary to achieve high output parameters of laser radiation. Such conditions include the partial pressures of the components of the Sr-He working mixture, the pulsed energy input into the active medium, and the pulse repetition rate. The research results can serve as a guideline for optimizing the operating modes of recombination lasers.
Keywords: strontium vapor laser, recombination pumping, numerical modeling, optimization