Modeling ion flux coefficient in high ion concentrated dusty plasmas using Langevin Dynamics simulations

The influence of dense and strongly coupled ions on the ion current to a particle is modeled in this work. LD is used to simulate the motion of N ions around a negatively charged grain in a periodic domain. The ion flux coefficient, β, is calculated using the grain-ion collision time distribution. In addition to the ion-ion electrostatic coupling strength Γ=e²/(4πε₀k_BT_in_i^-1/3), β is also influenced by the diffusive Knudsen number Kn_D=(m_ik_BT_i)^1/2/f_ia_p that characterizes the ion-neutral gas interactions (through the scalar friction factor f_i), a concentration parameter χ=a_p/n_i^-1/3 that compares the size of the grain a_p to the mean inter-ion spacing n_i^-1/3, where n_i is the ion number density and Ψ_E=-z_pΓ/χ that denotes the strength of particle-ion interaction. The influence of Kn_D on the structure and self-organization of ions is demonstrated by analyzing the ion-ion pair correlation function and velocity distribution function. The model for β is presented as the ratio of the computed value to that obtained using a dilute charging model. The model will be validated against suitable experimental data from the literature.