Water vapor generator with periodically-changing pressure

The invention belongs to the field of chemical experiments and particularly relates to an air pressure generator. The technical scheme of the water vapor generator with the periodically-changing pressure is as follows: a water bath is connected with one end of an air inlet pipeline; the other end of the air inlet pipeline penetrates through an infrared sample bin and is communicated with a sample cell; one end of an air outlet pipeline is communicated with the sample cell; the other end of the air outlet pipeline penetrates through the infrared sample bin and is connected with a vacuum pump; a barometer is mounted on the air inlet pipeline; a hygrometer is mounted on the air outlet pipeline; an air inlet cut-off valve is arranged on the air inlet pipeline between the barometer and the water bath; an air outlet cut-off valve is arranged on the air outlet pipeline between the hygrometer and the vacuum pump; and a pressure control center is respectively connected with the air inlet cut-off valve, the barometer, the hygrometer and the air outlet cut-off valve. According to the water vapor generator disclosed by the invention, the pressure of water vapor periodically changes and meets the condition of stepped scanning; the number of water molecules generating reaction can be quantitively controlled by controlling the pressure of water vapor; the water molecules react with quantitive aerosol particles; and a strictly-repeated chemical reaction environment is provided.