Infrared continuum radiation from metal halide high intensity discharge lamps

Abstract

Infrared (IR) continuum radiation from the arc of a metal halide high intensity discharge lamp was measured and modelled. There are three contributions to the near IR continuum from free electrons: electron–Hg atom bremsstrahlung, electron–ion bremsstrahlung and electron–ion recombination radiation. Electron–Hg atom bremsstrahlung is the most important of these. The radiation transport model utilized empirical Hg density, arc temperature and electron density maps. The line width of the Hg 71S0 to 61P1 resonance broadened transition was used to determine the arc core Hg density. The arc temperature as a function of radius was determined using the radiance of the Hg 9860, 7311 and 7166 cm−1 lines. Relative densities of neutral Dy atoms and Dy ions as a function of radius were found using an Abel inversion of the relative line radiance of selected Dy I and Dy II lines. A Saha analysis was used to determine the electron density in the lamp. The continuum is 73% of the total near IR radiation in the 4000–12 800 cm−1 range.

A survey of infrared continuum versus line radiation from metal halide lamps

“…Part of the motivation for this survey was to establish both similarities and differences between the Broadway Star lamp and other lamps. A 200 W Broadway Star lamp was chosen for detailed studies of the microscopic physics of near-IR continuum mechanisms [9]. In the case of the Broadway Star lamp the strong near-IR continuum was found to be largely from electron+Hg atom bremsstrahlung [9].…”

“…A 200 W Broadway Star lamp was chosen for detailed studies of the microscopic physics of near-IR continuum mechanisms [9]. In the case of the Broadway Star lamp the strong near-IR continuum was found to be largely from electron+Hg atom bremsstrahlung [9]. This Broadway Star lamp is somewhat similar in performance to modern ceramic MH-HID lamps with rare earth doses.…”

“…This setup was used in measurements of the ratio of near-IR continuum to line emission. The set-up for spectral radiance measurements was also used in related work by Herd and Lawler [9].…”

“…We found that the continuum is always significant, and it dominates near-IR losses from MH-HID lamps with rare earth doses. One of these rare earth MH-HID lamps was recently used in a more detailed study of the microscopic physics of continuum mechanism [9].…”

A calibrated integrating sphere setup to determine the infrared spectral radiant flux of high-intensity discharge lamps

“…Infrared radiation, either in the form of radiation from the plasma or in the form of thermal radiation from the burner wall, can consume 50-75% of the total input power. The ALITE-II project's [6] primary focus was the infrared radiation of HID lamps; several papers regarding the infrared radiation from HID lamps have recently been published [7][8][9]. In these papers the focus was mainly on the continuum radiation generated by the plasma.…”