Modeling of aluminum impurity entrainment in the PISCES-A He⁺ plasma

A 1D theoretical model describing transport of Al impurities in a low temperature He⁺ plasma is discussed. The model adopts a kinetic approach to describe impurity entrainment in a steady state He⁺ plasma flow. Results of a 1D Monte Carlo simulation supporting this model are presented and compared to experimental data collected from PISCES-A linear experiment. Both simulation and experimental results confirm that impurities are quickly entrained by the background plasma and quickly acquire its flowing velocity. However, a major discrepancy is observed in the temporal width when comparing the simulation to the experimental Al²⁺ density profiles downstream the flow. Consideration of several potential effects suggests that background plasma velocity shear is the most likely cause for this discrepancy