Trojan Technologies uses ultraviolet (UV) lamps in reactors to purify water. When multiple lamps in a reactor are active at once, light emitted by the various lamps can interact with neighbouring lamps, creating effects that are not well taken into account in current industrial lamp models. The goal of this project is to develop a more accurate model, which accounts for these phenomena, to better predict the distribution of UV light inside a reactor. To do this, we have developed a numerical model of the photon-plasma interactions, which agrees well with work found in the literature.