The main goal of the research is evaluation of the plasma jet driven magneto-inertial fusion (PJMIF) concept via simulations. To achieve this goal, the development of mathematical models and numerical algorithms for PJMIF has been performed, and large-scale simulation studies have been conducted. In the PJMIF concept, a plasma liner, formed by the merger of a large number of radial, highly supersonic plasma jets, implodes on a magnetized plasma target and compresses it to conditions of the fusion ignition. 1- (spherically symmetric), 2- and 3-dimensional simulations of the implosion of plasma liners and compression of plasma targets have been performed using the FronTier code based on the method of front tracking. Scaling laws and related fusion theories have been investigated and their conclusions compared with our results. Compared to previous theoretical and numerical studies of PJMIF, our numerical models and algorithms implement several new physics models important to PJMIF. One of them is a numerical model for atomic physics processes. The influence of atomic physics processes on the plasma liners for magneto-inertial nuclear fusion has been studied based on equation of state models with dissociation and ionization. These atomic processes in imploding liners reduce the temperature and increase the Mach number of liners, result in higher stagnation pressure and the fusion energy gain. Other factors influencing liner implosion are the residual vacuum gas and heat conduction. By replacing the idealized vacuum region with realistic residual gas and adding the Spitzer electronic thermal conductivity, we quantified their effects in the low-energy simulation regime. We have demonstrated that the internal structure of argon plasma liners, formed by the merger of plasma jets is strongly influenced by a cascade of oblique shock waves generated by colliding jets. Corresponding studies have been performed using 2- and 3-dimensional simulations. 10 times reduction of the stagnation pressure was found compared to spherically symmetric liner with the same pressure and density profiles at the merging radius, due to the influence of oblique shock waves and adiabatic compression heating. The experiment results of single argon plasma jet propagation and two argon plasma jets merger reported by Plasma Liner Experiment group in Los Alamos National Lab have also been compared with our simulations. A multi-stage computational approach for simulations of the liner-target interaction and the compression of plasma targets has been developed to minimize computing time. Simulations revealed important features of the target implosion process, including instability and disintegration of targets. The non-uniformity of the leading edge of the liner caused by the oblique shock waves between jets leads to instabilities during target compression. By using front tracking, the evolution of targets has been studied in 2- and 3-dimensional simulations. Optimization studies of target compression with different number of jets have also been performed.
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- Physics, Radiation;Physics, Fluid and Plasma;Applied Mathematics