Radiation from an alternating current high-pressure mercury discharge:: A comparison between experiments and model calculations

An alternating current (ac) high-pressure mercury arc has been experimentally investigated, and the results have been compared with model calculations. In the model, only radial dependencies are considered, and a careful treatment of the radiation transport is included. The absolutely measured side-on radiance in the visible and near ultraviolet spectral range can now be quantitatively reproduced by this model starting from the measured arc current. Agreement between the measured and calculated radial temperature profile can be obtained only by taking into account the time-dependent behavior of the investigated ac arc. The calculated field strengths agree with the measured ones only if more recent values of momentum transfer cross sections for the calculation of the electrical conductivity of mercury have been used. The time-dependent pressure in the discharge is determined via the electrical conductivity using Ohm's law, the radial temperature distribution, and the electrical field strength. (C) 1999 American Institute of Physics. [S0021-8979(99)04210-3].