Theoretical modelling of high pressure argon arc radiation

A one-dimensional, axisymmetric, high-pressure argon arc was modelled theoretically, and its radiation spectrum was calculated numerically from the equations of heat conductivity and radiation transfer. For a pressure of P = 15 atm, the coefficients of absorption in argon were calculated for the continuum and line spectra. The coefficient of radiative heat conductivity was found, subject to the assumptions that the continuum optical depth is less than unity while the line optical depth is much more than unity. The general heat conductivity was found by neglecting convection, but taking into account radiative conductance and kinetic conductance by ions, electrons and neutral atoms. The radial distributions of the temperature, ionization degree and electrical conductivity were found for arcs with currents I = 880, 990 and t250 A confined in a transparent tube of radius R = 0.01 m. The degree of ionization was calculated assuming local thermodynamic equilibrium. An effective temperature was calculated in the spectral region of 300-3000 nm. For I = 880 and 1250 A, the effective temperatures were found to be 7500 and 8700 K and the maximum spectral radiant intensities were 7.5 × 10^-8 and 10.5 × 10^-8 W m^-2 Hz^-1, respectively.