An investigation into radial gradients in an eletrothermal plasma source using a semi 2-D approach

Summary form only given. Small aspect ratio capillary discharges (r/L≪0.5) are reasonably modeled using 0-D and 1-D, time dependent models and scaling laws. However, a 2-D, time dependent model would be more suitable when further details are needed on the gradients in the plasma parameters near the wall of the capillary, especially in applications where a larger diameter source is needed. It is also of importance to develop a 2-D model to better couple source models to large chamber or barrel models that require 2-D or 3-D treatment such as plasma flow in solid propellant charges in large chambers. In this study the 1-D capillary discharge code ETFLOW has been modified to model the plasma flow inside of an electrothermal capillary discharge in order to understand the behavior of the radial plasma gradients inside of the source. This model is an approximated form of a 2-D model that includes radial terms for heat conduction, heat conduction effects on wall ablation, plasma electrical conductivity, and other plasma parameters. The code also includes both ideal and non-ideal models for the Coulomb logarithm, which allows for more accurate determination of the plasma conductivity in different operating regimes. The code solves the axial flow conservation equations followed by the radial equations and combines the solution to provide an approximated 2-D picture of the radial and axial plasma gradients. Several case studies for benchmarking and comparison to physical experiments have been performed. The code, ETFLOW2D, has shown results consistent with both physical experiments and previous 1-D ETFLOW results.. Additional case studies using metals and composite materials have been conducted to evaluate the effects of including various parameters in the conservation equations.