Fluorescent tube with inert and halogen gas mixture - has spiral incandescent element and feedback tube coated with heat reflecting layer

An elongated fluorescent tube is filled with a noble gas and a halogen. In addition to the actual combustion chamber there is an additional feedback pipe for the filler gas. The feedback pipe consists of a tube running along the outside of the cylindrical bulb. The elongated bulb (1) contains a spiral incandescent element (2) made from tungsten which runs along the axis. The wall of the feedback tube partly coincides with the wall of the bulb. The feedback tube is coated with a heat reflecting layer. The inert gas used can be argon, crypton, or senon or a mixture of any of these gases. This gas is mixed with either pure iodine, bromine, chlorine, fluorine or a mixture of any of them.