Study on the Influence of Excited States on the Particle Composition of Air Arc Plasma

The particle composition of arc plasma is a prerequisite parameter for calculating its physical parameters and numerical simulation. Taking 78%N2–22%O2 mixed gas as an example, this paper studies the influence of considering particle excited states on the calculation results when calculating the particle composition of equilibrium arc plasma based on quantum chemical calculations. The stable structures and excited states of particles were calculated by quantum chemical methods, and then the particle composition of equilibrium arc plasma was calculated. The particle composition distributions obtained by ignoring excited states, calculating excited states using time-dependent density functional theory (TDDFT), and calculating excited states using complete active space self-consistent field (CASSCF) were compared. The influence of excited states on particle composition distribution was analyzed, and appropriate calculation methods for excited states were studied. The results show that with the increase of arc plasma temperature, the influence of excited states on particle distribution gradually increases. Finally, a hierarchical method for obtaining excited state parameters is proposed: NIST atomic spectroscopy database excited state parameters are used for single atoms and their positive ions; CASSCF method is used for single atomic negative ions and diatomic particles; TDDFT method is used for polyatomic particles.