Oxidation of SO₂ and formation of water droplets under irradiation of 20MeV protons in N₂/H₂O/SO₂

摘要

We have performed an experiment on charged droplet formation in a humidified N gas with trace SO concentration and induced by 20MeV proton irradiation. It is thought that SOreacts with the chemical species, such as OH radicals, generated through the reactions triggered by N production. Both droplet number and droplet size increased with SOconsumption for the proton irradiation. The total charged droplet numbers entering the differential mobility analyzer per unit time were proportional to the 0.68 power of the SO consumption. These two findings suggest that coagulation among the small droplets contributes to the formation of the droplets. The charged droplet volume detected per unit time is proportional to the SOconsumption, which indicates that a constant amount of sulfur atoms is contained in a unit volume of droplet, regardless of different droplet-size distributions depending on the SO consumption.