Abstract
This paper discusses the thermal behavior of a high-intensity mercury lamp in a horizontal position, compared with that of a vertical lamp when the pressure of the lamp varies. The model adopted is 3-D, steady, and direct-current powered. After the model validation, we keep the supply current equal to 3.2 A, and we vary the pressure of the lamp to 10 5 - 10 6 Pa. Then, we analyzed the temperature fields, the heat conduction flow, the convective flow, and the accumulation of mercury behind the electrodes for the case of the lamp in a horizontal position by comparing it with those of a lamp in a vertical position.