Numerical Simulation of Merging Plasma Jets Using High-Z Gases

Some initial numerical studies of merging plasma jets for magneto-inertial fusion (MIF) and high-energy-density laboratory plasmas have been performed, focusing on the study of jet propagation and plasma liner formation. Being heavier for a fixed number density and with more radiation cooling, high-Z materials can keep low jet transverse Mach number, and they are preferred in our studies as plasma jet and liner materials, while four-jet mergings of hydrogen and helium are briefly studied for comparison. Because of the advantages of high-Z plasma jets for the MIF application in which we are particularly interested, we focus mainly on argon and xenon in this paper. The plasma jets propagate with an initial velocity of 50-100 km/s, and number density is in the range 10¹⁶ to 10¹⁷ cm^-3. The merging jets are several centimeters in diameter. The hybrid particle-in-cell code LSP is used to perform the simulations, using an advanced fluid algorithm with equation-of-state model and a radiation transport model. Simulation results for several configurations and different numbers of the merging jets are compared and discussed. The results show that, with same number density, jet velocity, and temperature, merging using more jets achieves higher density, such as an amplification ratio of 115 for 16 jets and 38.5 for 4 jets, and much higher than that of hydrogen and helium in four-jet merging. During these mergings, the electron pressure reaches up to 10, 22.5, and 33.5 bar, respectively.