Marc

Are "Xenon" headlights the same as "Halogen"?

HermanH

Actually, "burn" is NOT the correct term to use. All headlamps incoprorating any type of hallide or inert gas, utilize electricity to "excite" the molecules; depending upon the type of gas and the amount of electricity utilized. That's about all the Chemistry I can remember. I guess Xenon get's brighter than Halogen when given enough electrons flowing though the gas. I don't know what the HID lamps contain.<p>HermanH

Kyle Bailey

I'm no expert, but it was just explained to me this morning. Halogen gas essentially allows the tungsten filament to burn hotter (thus whiter) without reducing the life of the bulb by redepositing some of the tungsten on the filament. A chemist will have to give us the full explanation.<p>As I understand it, the HID bulbs are arc lamps and there is no filament. Xenon is the gas used to give the color characteristics. There is no filament involved.<p>Kyle

Marc

Thanks for that, it really helped!

Brad Franklin

You're correct. Standard bulbs consist of a tungsten filament surrounded by some sort of inert gas, often Argon. Halogens have the same basic structure, but have a few perks to keep them around longer. The gas inside of a halogen bulb is...well...a halogen (often iodine, most of the other gases are extremely lethal, like flourine and chlorine). With a normal bulb, atoms from the tungsten filament slowly evaporate from the surface while it burns, and can actually coat the inside of the bulb. The halogen gas inside the halogen bulb bonds to the tungsten atoms being released by the filament. After a short while, the bulb will be filled not with a halogen gas, but a halide gas (halogen compound, like tungsten iodide) due to the reaction between the gas and the evaporated tungsten atoms. Well when those halide molecules get near the hot tungsten filament, the heat breaks them apart and re-deposits the tungsten onto the filament, thus extending the life of the filament and preventing the tungsten from coating the inside of the bulb (supposedly makes it brighter after a long time, not sure how much difference this makes). A Xenon system is an arc lamp system. There is no physical filament in these things, they're more like a flourescent lamp or neon bulb. Essentially you have a cathode and anode inside a bulb filed with the noble gas Xenon. Voltage from the car is stepped up to maybe a few thousand volts (just a guess, I'm not really sure what voltage they use, but it's high) , enough to make electrons jump from the anode to the cathode through the Xenon gas. As the electrons travel through the gas, they collide and energize the Xenon atoms floating around. This excites their electrons to a higher energy state. In this higher energy state, the Xenon atoms' electron shells are unstable, so they collapse back to their original configuration. The excess energy is released in the form of photons, a bluish sort of light from Xenon. If you ever see someone turn on their Xenons, they don't just flip on instantly like a filament system. Rather they sorta slowly come about, kinda neat looking. The reason why you can't easily upgrade your existing lights to Xenons is the whole apparatus that ups your voltage to a high enough potential to make the lights function. This is probably the most expensive part too (aftermarket conversions to Xenon run around $2000). <p>Brad