Why can halogen lamps operate at a higher temperature than incandescent light bulbs?
Halogen lamps require a few special considerations that allow them to operate at high temperatures. One is a bulb casing that won’t crack at high temperature differences. The inside of the bulb is blazing hot, whereas the outside is much closer to room temperature. Most materials expand on heating, and the tendency is for the inside to expand more than the outside, as the inside is much hotter. This creates stresses in the bulb and would lead to fracture. However, halogen lamps use a fused quartz bulb, which has a very low coefficient of expansion. This allows the casing to survive. However, there is another issue. Tungsten filaments operating at such high temperatures lose some of the filament material. This is where the “halogen” comes in. The tungsten that evaporates from the filament tends to deposit on the bulb, but the halogen gas will bind to the deposited tungsten and remove it from the bulb. Then the halogen-tungsten bound compound (still gaseous) will eventually run into the
