When xenon is excited, the temperature inside the gas discharge headlight lamp rises, evaporating the mercury and creating an electric arc.
Mercury and the electric arc cause a further increase in temperature inside the lamp, the iodide evaporates and decomposes, the metal atoms release their accumulated energy, producing light.
Fig. 7.13. Design of a gas discharge headlight: 1 – B +; 2 – gas discharge headlight control unit; 3 – conclusion; 4 – gas discharge headlight bulb; 5 – xenon gas; 6 – metal atoms; 7 – iodide; 8 – mercury; 9 – light