Why the iodine-tungsten lamp has a small volume, High luminance, long service life?
Since Thomas Eison, the United States inventor, invented the electric light until now, humans have conducted many studies and improvements on the small light bulb. Vacuuming the bulb into a vacuum can prevent the filament from oxidizing, and then refilling it with inert gas (such as acetone) can reduce heat evaporation of the tungsten wire. But the lifespan of this bulb is still not long; taking a while, its luminance will also weaken gradually. This is because when the tungsten wire glows, the tungsten on the surface gradually sublimates, the tungsten vapor runs to the inside of the bulb when cold turns into solid tungsten deposited on the glass ball, making the shadow dark. At the same time, the tungsten wire became thinner and thinner, eventually falling off.
To prolong the bulb’s life, to eliminate the black phenomenon, people continued to study, finally to create an iodine-loaded incandescent lamp, in short, an iodine-tungsten lamp. It does not resemble ordinary filament lamps that are spherical. Its appearance is tubular. The lamp tube is made of quartz. Quartz can withstand high temperatures.
When the iodine-tungsten lamp works, the tungsten’s surface will still undergo such sublimation, producing tungsten vapor. However, when the temperature is at 250 ° C or higher, tungsten vapor can merge with the iodine in the tube, producing tungsten iodide (WI). This will stop the tungsten on the bulb. The very high temperature of the tungsten iodide near the filament (above 1400 ° C) dissociates immediately into iodine and tungsten. So the corroded tungsten is returned to the filament. The iodine in the tube constantly brings sublimated tungsten back from the filament, extending the lamp’s life. To ensure that tungsten and iodine can mix, the lamp’s temperature should not drop below 250 ° C. Therefore, the tube of an iodine-tungsten lamp cannot be large; the structure is always very compact.
The iodine-tungsten lamp is small in volume and has iodine as the “transport soldier” the temperature of the filament can also be raised. That improves luminance and glare efficiency.
The use of the tungsten – iodine lamp is very widespread. In addition to light the airport runway, soccer field, square, factory, street, theater, it can also be used for projection, photography, etc. Both gentle, safe, effective fruit is high again. Since iodine-tungsten lamps produce more ultraviolet radiation than conventional filament lamps, when the illuminated object is sensitive to ultraviolet rays, more attention must be paid to the attention. If bromine is loaded into the lamp tube instead of iodine, it can be turned into a bromine – tungsten lamp. The working principle of a bromine-tungsten lamp is the same as that of an iodine-tungsten lamp. Since iodine and bromine are both halogen elements, the iodine-tungsten lamp and the Brom-tungsten lamp are collectively referred to as a tungsten-halogen lamp.