The bulb is filled with gas, which is generally a chemically stable gas. Its purpose is mainly to reduce the volatilization of the filament and extend its service life. The most is nitrogen, but also filled with inert gas.
LED Bulb are generally chemically stable gases. Their purpose is mainly to reduce the volatilization of filaments to extend their useful life. The most common is nitrogen, which is also filled with inert gas. Conventional
halogen Bulbs are difficult to achieve.