High Pressure Mercury Vapour Lamp Spectrum

They require a shorter arc length.

High pressure mercury vapour lamp spectrum.

A metal halide lamp is an electrical lamp that produces light by an electric arc through a gaseous mixture of vaporized mercury and metal halides compounds of metals with bromine or iodine it is a type of high intensity discharge hid gas discharge lamp. The sodium is mixed with other impurities to create a more white light. Developed in the 1960s they are similar to mercury vapor lamps but contain additional metal halide compounds in the quartz arc tube. The sodium vapor strikes an arc over 240 c.

The mercury helps add a blue spectrum light to the pure yellow of the sodium. Charles wheatstone observed the spectrum of an electric discharge in mercury vapor in 1835 and noted the ultraviolet lines in that spectrum. High pressure mercury vapor arc lamps a type of high intensity discharge lamps are operated with a pressure of the order of one atmosphere and with much increased power densities so that more mercury is evaporated the high density of the vapor allows for light emission with a much higher radiance. In 1860 john thomas way used arc lamps operated in a mixture of air and mercury vapor at atmospheric pressure for lighting.

Low pressure and high pressure low pressure sodium lamps are highly efficient electrical light sources but their yellow light restricts applications to outdoor lighting such as street lamps where they are widely used. Later cooper hewitt mercury vapor tubes and historic fixture. Liquid mercury droplets collect at the lamp s cold spot once the mercury droplets reach their peak temperature maximum uvc output occurs. In such lamps there is also much stronger spectral broadening.

A sodium vapor lamp is a gas discharge lamp that uses sodium in an excited state to produce light at a characteristic wavelength near 589 nm. Two varieties of such lamps exist. Another version of the sodium arc lamp the low pressure sodium discharge lamp is the most efficient lamp known today in turning electricity into. Because their output is much more pleasant to look at they have replaced mercury vapor in streetlight applications.

The lamp heats and the sodium is the last material to vaporize. High pressure sodium lamps producing up to 150 lumens per watt produce a broader light spectrum than the low pressure sodium lamps. High pressure sodium lamps turn 50 of the electrical energy into visible light. High pressure mercury vapor lamps are the oldest high pressure lamp type and have been replaced in most applications by metal halide and the high pressure sodium lamps.