Some aspects of the tin halide molecular arc

Abstract

A high pressure gas discharge lamp with excellent colour rendering can be produced by exploiting the radiation from a tin halide arc. Radiation generation and transfer processes in the tin halide arc are reviewed and problems due to arc instabilities and horizontal operation are discussed. Magnetic stabilization enables the arc to be operated horizontally; a very small magnetic field of about 100 A/m is adequate. The choice of lamp filling is discussed in relation to optimization of luminous efficacy and control of the correlated colour temperature. Chromaticity is improved by the addition of lithium or indium. The influence of impurities on lamp performance is discussed, and the results of experiments on test lamps are presented. There is little decrease in luminous flux with time.