(304g) DSMC Simulation of Collision Process in Argon-Nitrogen Mixed Thermal Gaseous Plasma.

Authors : Sahadev Pradhan, A. K. Kalburgi

Affiliation : Chemical Technology Division, Bhabha Atomic Research Centre, Mumbai- 400 085, India.

Abstract:

The collision process in Argon-Nitrogen mixed thermal gaseous plasma consist of electrons and heavy particles is studied using Direct Simulation Monte Carlo (DSMC) simulations to understand the effect of large mass ratio (electron and heavy particles) on collision rate when each species specified as a separate collision group as well as all the species in a single group, for number of simulated particles per cell (F_N) in the range 2 < F_N < 200, with eight sub-cells per cell. By including the separate collision group for each species, the collision rates between heavy particles, between electrons, as well as among electrons and heavy particles with F_N = 200 and 20 are in excellent agreement with the theoretical value (N_pq)_eq= 2π^1/2{(d_ref)_pq}² n_p n_q {T/(T_ref)_pq}^1-É·_pq {2k_B (T_ref)_pq /m_r}^1/2 , to within 1%. However, the mean spacing between collision pair is increased and the selection is forced beyond the sub-cell. This also leads to an increase in the overall acceptance rate of collision pairs. The maximum value of the parameter, collision cross-section times relative velocity (σ_T C_r)_max have been studied to establish the proper collision rate and to make the selection process efficient. The comparison reveals that the inclusion of all the species in a single group become overwhelming when electrons are present. The very low F_N value (F_N =2) results in an excessive increase in mean spacing between collision pairs, and the error in the collision rate turn out to be very significant.

Key words: Collision Process, Electron and heavy particles, Thermal gaseous plasma, DSMC simulations