铜蒸气对CO₂电弧等离子体物性参数的影响

Due to the advantages of low potential for global warming and high thermal conductivity at low temperatures, CO₂ is regarded as a kind of potential alternatives of SF₆ and has been gradually adopted by gas circuit breaker serving as an arc-extinguishing medium. The copper vapor from electrode erosion modifies the fundamental characteristics of the arc and consequently affects the interruption performance of circuit breakers. Thus, utilizing the Gibbs free energy minimization method and Chapman-Enskog theory, we calculated fundamental properties of CO₂-Cu arc plasma at a pressure of 0.5 MPa and temperature of 2 000~30 000 K and investigated the effects of copper concentration on species compositions, thermal properties and transport coefficients. It is found that the ionization of copper from electrode erosion occurs earlier than other nonmetallic atoms, which increases the electron number density in the mixture even if the copper concentration is small (5%), and consequently the electrical conductivity at low temperature (below 8 000 K) is enhanced with a maximum upgrade of about an order of magnitude. Increasing copper concentrations leads to the increase of mass density and decrease specific heat, viscosity and thermal conductivity in the whole temperature range. However, opposite effects of increasing copper concentrations are observed. The influence of copper vapor of a small proportion (5%) is minimal for fundamental plasma properties except for electrical conductivity unless the copper concentration is evaluated up to 25%. These calculated results have reference values for investigating the effects of copper concentrations on physical property parameters of the CO₂ arc and can provide input parameters for magnetohydrodynamics (MHD) models for CO₂ arc considering electrode erosion.