The xenon lamp in a photochemical reactor is a photoelectric tube or flash lamp filled with xenon gas. Xenon is chemically inactive, cannot burn, and does not support combustion. It is natural rare gas with high molecular weight and high density. Xenon high-pressure lamp radiation emits strong ultraviolet rays, which can be used in medical treatment and make spectrometer spectrum. Xenon lamps are also commonly referred to as pulsed xenon lamps and laser xenon lamps. It is widely used in laser marking, laser engraving machine, laser welding machine, laser engraving machine, laser tattoo removal machine and other laser equipment. Xenon lamp is a kind of lamp with high luminous power and close to daylight. It is divided into three types: long arc xenon lamp, short arc xenon lamp and pulse xenon lamp. The long-arc xenon lamps are all made into a tube. The lamp tube is made of high-temperature resistant, low thermal expansion coefficient fully transparent quartz tube. Two thorium tungsten (or barium tungsten) electrodes are sealed at both ends. The distance between the electrodes is generally greater than 100 mm. The tube is filled with High purity xenon gas. The structure of the water-cooled long-arc xenon lamp is shown in Figure 5-20. The arc discharge of a long-arc xenon lamp depends on the breakdown of high-frequency and high-voltage pulses to start. Under the action of high-voltage pulses, a spark discharge channel is initially formed in the lamp tube, and the electrons and ions generated thereby continue to ionize neutral gas molecules and atoms under the action of an electric field, and an avalanche process occurs. Under the impact of ions, the electrode is heated to become a thermal emitter, emitting a large number of thermal electrons, which generates a large current, and then forms a stable arc discharge. Because it is a high-pressure gas discharge, the discharge current is usually high-temperature plasma.