Numerical simulation of the basic parameters of a discharge plasma based on a mixture of mercury diiodide vapor and argon


Introduction. In our previous studies have been found that in barrier discharge plasma based on mercury diiodide vapor with neon mixture mercury monoiodide exciplex molecules are formed. Emission of these molecules is occurring in violet - blue spectral range (λmax = 444 nm) and have been revealed that only a mixture of mercury diiodide vapor with helium is more efficient (radiation power in spectral band with a peak wavelength 444 nm).
Purpose. The aim of research was to determine the plasma parameters in mixtures as mercury diiodide vapor with argon.
Methods. Plasma parameters were determined numerically based on the electron energy distribution function (EEDF) in discharge. EEDF was determined by solving the kinetic Boltzmann equation in two-terms approximation using well-known program "Bolsig +". Based on EEDF: mean electron energies, specific power losses of electrical discharge and rate constants of elastic and inelastic scattering of electrons on mercury diiodide and argon atoms as a function of the reduced electric field were identified.
Results. Established: electron energy distribution functions, mean electron energies, specific losses of discharge power on electronic processes and rate constants of processes: elastic and inelastic scattering of electrons on the components of the mixture depending on the value of the reduced electric field. For mercury diiodide vapor and argon mixture portion of discharge power, that is spent on the process of mercury monoiodide molecules excitation reached a maximum of 99% at the value of the parameter E/N equal to 15 Td for B2Σ+1/2 electronic state. The rate constant of B2Σ+1/2 –state excitation is equal to 1·10-24 – 1,6·10-17 м3/c for the reduced electric field E/N = 15 - 100 Td.
Conclusion. The numerical simulation results give the reason to conclude about the possibility to increase the radiation power in the violet-blue spectral range of the multi-wavelength DBD-driven exciplex lamp based on a mixture of the mercury diiodide vapours and argon by means of the reduction of the parameter E/N to the value of 15 Td

Keywords: gas discharge plasma, radiation of exisplex molecules, plasma parameters, mercuric diiodide, argon