Correct, instead of using a filament to create the light, and electrical charge is passed thru the gas to create a glowing arc. Sodium vapor lamps (Like street lamps or those in stadiums) are not well suited for auto applications due to their yellowish tinge and large ballast.Originally posted by Kompressor:
Someone told me they're simiilar to stadium lighting HIDs, which use Mercury and sodium vapors. But if you've ever seen those lights start up, they take a good 3 or 4 minutes to light up to 100%. To solve that start up problem in car lamps, Xenon was used.