Abstract: When particle groups are injected directly into a plasma torch, the influence of the particle groups on the arc plasma is an important factor in the design of the plasma torch. This paper introduces the P-1 radiation model, which is used to describe the radiation between particle groups. Combined with the P-1 radiation model, the Elenbass-Heller equation is modified and then solved to probe into the radiation influence of the graphite particle groups on the volt-ampere characteristics of the arc plasma. The results show that the radiation of the graphite particle groups increases the heat conductivity of the arc, the arc is compressed by cooling down, and the intensity of the electric field of the arc increases. At the same time, the effect of particle group radiation on the intensity of the electric field is more evident along with the larger arc channel radius. Moreover, the effect on the argon arc plasma is much larger than its effect on the hydrogen arc plasma. It is recognized by the calculation of the particle radiation that the particle group radiation mainly plays an important role in the location near the wall. At the edge of the cold wall, the particle group radiation functions as net absorption, and the heat transferred to the cold wall is reduced.

Key words: arc plasma, particle group, P-1 model, voltage-current characteristic