What Gas Is Used in Light Bulbs?

Edison's Incandescent

The first incandescent lamps used carbon-bamboo filaments to "incandesce" in resistance to an electrical current. The bulb that held the filament was made of hand-blown glass. As physicists worked with the insides of the light bulb, developing long-lived tungsten-based filaments, they also discovered that a true vacuum was very difficult to achieve, making the light bulbs expensive to produce. They also discovered that oxygen in the air caused the filaments to disintegrate more rapidly, but that the introduction of certain noble gases seemed to increase the life of the filament. The standard light bulb as we know it today uses an atmosphere of nitrogen and argon, and is more efficient than Thomas Edison's original---but it still loses more energy in heat than it generates in light.

Twentieth-Century Technology

Throughout the 19th century, scientists had worked on ways of generating electricity. Then, at the very beginning of the 20th century, Edison marketed his light bulb. Edison, Nikola Tesla and others had experimented with using gases that "fluoresced," or glowed, without the need for a filament, but one of Edison's employees, Daniel Moore, developed the first fluorescent lights, using carbon dioxide and nitrogen. A contemporary of Moore, Peter Cooper-Hewitt, developed the practical fluorescent, using a gaseous form of mercury. Research using neon introduced the concept of coating the inside of the florescent tube to correct the color of the fluorescing gas. Throughout the 20th century, new uses were found for fluorescent lights in industrial and commercial lighting, with mercury vapor as the standard for general illumination. Neon and other gases that did not create enough illumination were adapted for functions in the arts and entertainment worlds.

Improvements on Existing Technology

Throughout the 20th century, improvements were made to existing technologies. The incandescent lamp, the least-efficient type of lighting, was upgraded by the replacement of argon with krypton and xenon, also noble gases. These gases repel the electrons that are lost by the burning tungsten filament as it burns, bouncing them back to repair the disintegrating metal. The expense of krypton and xenon lamps, however, limits their marketability. Halogen gases, such as iodine, fluorine and bromine, are used in incandescent lamps called tungsten-halogen or halogen bulbs. They restore electrons by trading back, also improving the efficiency of the incandescent lamp. These small lamps, encased in quartz bulbs, burn brighter than noble gases, making them more efficient, but they also burn hotter, limiting the places where they can be used. The most efficient of the existing lamps that use gases, though, is still the mercury-vapor fluorescent, which is adapted with electronic ballasts to make lamps called compact fluorescent lamps (CFL) that can be used in common domestic fixtures. Some lamps employ variations on fluorescent theory; sodium-vapor or mercury-vapor streetlights or metal halide lamps (combining halogen and noble gases) use gases kept at high pressure. Other lights, such as black lights, use complex combinations of gases and coated bulbs to achieve specific colors or qualities of light.

Resources

• Fluorescent Light Bulbs Primer
• The Great Internet Light Bulb Book, Part I
• Black Lights and Neon Lights