A theoretical treatment of the line-intensity jump in a decaying argon-arc plasma

The line-intensity jump in decaying argon arcs has been investigated theoretically. The population density at the peak of the jump is in Saha-Boltzmann equilibrium. Using the Saha-Boltzmann relation, the influence of the change in electron density is clarified. As a criterion above which the change in electron density does not influence the amplitude of the jump, τ_N/τ_T ≧ 10₃ is derived, where τ_N and τ_T are, respectively, the density and temperature relaxation times for the electrons. This criterion is not satisfied in most arcs. An improved method is presented for the determination of the gas temperature in stationary arcs.