Comparative characteristics of high-pressure arc radiation in argon, krypton and xenon atmospheres

Axisymmetric, high-pressure arcs in argon, krypton and xenon atmospheres, were theoretically modelled, and their radiation characteristics was calculated numerically using the equations of heat and radiation transfer. The coefficients of radiative absorption for these three gases were calculated both for the continuum spectra and selected spectral lines, for an arc pressure of 15 atm. In the case of the high-frequency region, ν ≥ χ0/h, where ν is the frequency, h is Planck's constant and χ0 is the first ionization energy, a black body radiation distribution was assumed, due to a high absorption coefficient, while for low-frequency radiation, ν ≤ χ0/h, the radiation intensity as a function of the frequency is calculated. The radial temperature distribution as well as electrical conductivity and degree of ionization were derived for arc currents in the range 1200-7500 A, in arc plasma confined in a transparent tube of radius R 0.01 m. The radiative power Wrad in a spectral range of (6-30) x 103 A with an arc current of ∼1200 A was ∼3 x 106 W m-1 for each of the examined gases, while for an arc current ∼7500 A, it was ∼17 x 106 W m-1 for krypton and ∼13 x 106 W m-1 for xenon. The relative arc radiation efficiency, Wrad/WJoule, with an arc current of ∼ 1200 A, was largest for argon (35%) and smallest for xenon (18%), while at 7500 A the relative arc radiation efficiency for all the examined gases was ∼5%. The calculated arc radiation spectra are also presented