Radiation Mechanism for Chemically Active Plasma
Customer Goals and Requirements
One of the leading suppliers of fluorescent lightings in the Unite States and all over the world has initiated investigations aimed at improving lamp efficiency and removing mercury from lamps. Such investigations require the evaluation of numerous candidates in their ability to provide visible light with a high yield and good color rendering. This cannot be accomplished without a deep understanding of physical and chemical processes in plasma. The analysis of light radiation efficiency needs detailed primary information on the cross sections and probabilities of elementary processes and advanced tools for modeling the kinetics of non-equilibrium discharges in molecular gases.
Kintech Solution
Kintech Lab has developed a multiscale multiphysics approach to the prediction of plasma composition, emission spectra, and low-pressure gas-discharge power and performed an extended screening of promising radiation sources for luminescent lamps using the family of Kintech programs, Chemical WorkBench and Khimera. This approach serves an independent predictive research tool complementary to experimental techniques. It proved to be very useful for selecting the most efficient radiators and the best plasma conditions.
Integrated Procedure of the Predictive Modeling of Plasma Kinetics
- Ab initio calculations of unknown parameters for atoms, molecules, and their interactions
- Evaluation of cross sections, rate constants, and radiation parameters
- Construction of a physicochemical mechanism
- Kinetic modeling, mechanism reduction, determination of key kinetic stages
Below, the procedure is illustrated for the case of Ar–GaI3 low-pressure glow discharge.
Steps 2&3. Evaluation of rate parameters and mechanism construction.
Currently available methods of electronic structure calculations for molecules in the ground state and scanning potential energy surfaces were used to predict heats of reactions and activation barriers to within a few kcal/mol. Rate constants of direct thermal molecular reactions were accurately calculated using the standard transition state theory. Kinetic mechanism including neutral and ion-molecular reactions and also electronic processes was constructed.
Mechanism details see in M.Deminsky at al., J. Phys. D: Appl. Phys. 40 (2007) 3857–3881