When ordinary low-pressure ultraviolet sterilization lamp tubes operate, the low-pressure mercury vapor in the tube will be activated and emit 253.7 nm and 185 nm of ultraviolet germicidal lamp, and 253.7 nm of ultraviolet germicidal lamp is irradiated on the adjacent mercury atoms, which will produce resonance absorption effect and further release of ultraviolet germicidal lamp from the irradiated mercury atoms. With the accumulation of heat generated during the operation of the lamp tube, the temperature in the tube will rise, resulting in a rise in the vapor pressure of mercury in the tube and an increase in the concentration of mercury atoms. In the early stage of temperature rise, the resonance absorption effect will be enhanced, and the ultraviolet output of the lamp tube will be increased. But in the absence of amalgam, such as without good ventilation cooling conditions, with the tube. The temperature and the mercury vapor pressure rise further, the collision between the mercury atoms is increased, and the ultraviolet ray of 253.7 nm is rapidly suppressed to be emitted, and the ultraviolet output of the lamp tube is anti-falling. Therefore, for a common ultraviolet sterilization lamp tube, the ultraviolet output is strong, and an optimum mercury vapor pressure (generally 0.8 to 1Pa) exists in the tube, and a good ultraviolet output can be obtained only in such a narrow temperature range. For the common low-voltage ultraviolet lamp, the working temperature is about 40 ℃.