Abstract

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 neon for the values of mixture components partial pressures at which in the experiment the maximum value of the radiation power was obtained.
Methods. Barrier discharge 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, electron mobility, specific power losses of electrical discharge and rate constants of elastic and inelastic scattering of electrons on mercury diiodide, nitrogen molecules and helium atoms as a function of the reduced electric field were identified.
Results. Established: electron energy distribution functions, transport characteristics, 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 neon mixture maximum values of the electron density vary from 7.7·10¹⁵ m^-3 to 3.0 ·10¹⁶ m^-3 by changing the value of the parameter E/N from 1 Td to 100 Td. Electron temperature increased from 16239 K to 101302 K. Portion of discharge power, that is spent on the process of mercury monoiodide molecules excitation reached a maximum of 92% at the value of the parameter E/N equal to 4.4 Td for B²Σ⁺_1/2 electronic state. The rate constant of B²Σ⁺_1/2 –state excitation is equal to 2.2∙10^-14 m³/c for the reduced electric field E/N = 46 Td, at which in experimental conditions maximum radiated power in violet - blue spectral region (λmax. = 444 nm) was observed.
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 multiwavelength DBD-driven exciplex lamp based on a mixture of the mercury diiodide vapours, xenon and neon by means of the reduction of the parameter E/N to the value of 4.4 Td. To achieve this value of the parameter can be a combination of a high electric field pulse on discharge front and low field behind the front

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

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