Computational Study of the Wall Electrization Limiting Characteristics at the Low-Temperature Plasma Flow

Abstract

The purpose of this work lies in computational study of the floating potential distribution in the perturbed zone adjacent to the wall in the ionized flow of low-temperature plasma. As a result of electrophysical interaction, primary and secondary emission currents appear on the wall surface. Based on the probe theory, mathematical model was developed to determine the current values of the combustion products ionized flow and spatial potential on the surface of walls in the power plant flow path. Parametric calculation of the potential on the wall at its contact with the low-temperature plasma was carried out without and taking into account the secondary emission processes. The results obtained taking into account only the primary currents demonstrate alteration in the potential on the wall in the range of --(1.5--0.5) V at the plasma flow temperature of 1,000--3,500 K. Results are presented of the design research of the wall floating potential dependence with various secondary electron emission coefficients in comparison with the known experimental results. Metal walls were characterized by formation of a shielding layer, where only the primary currents appeared. It is shown that their floating potential changes the sign in dielectric walls, as coefficient of the secondary electron emission decreases. Parametric calculation of the current value near the wall was carried out showing that with an increase in pressure by 0.1--10 MPa, the current value was changing in the range of 0.005--0.025 A