Magnetized target plasma collision experiments for PLX: Diagnostics and Results*

HyperJet Fusion is building magnetized hydrogen plasma target formation guns for the PLX plasma liner-on-target plasma jet magneto-inertial fusion (PJMIF) scaling experiment at LANL. The target is made by stagnating multiple magnetized plasma jets. In order to reduce risk, a two-jet collision experiment is underway at HyperJet Fusion’s Virginia facility using two target guns to evaluate the collision dynamics of the magnetized hydrogen plasma jets. To diagnose the jets and the merged target plasma we measure velocity, T_i, density, and magnetic field. The diagnostics are interferometry, movable B-dot probe array, spatially resolved photodiodes, high speed imaging, and time resolved spectroscopy, both high resolution (for temperature and velocity) and survey spectroscopy (for line ratios and impurities). The impurity measurements are critical due to the impact on T_e during plasma compression. The initial level of impurities in two-gun collided experiments is ~3% as inferred from broadband visible spectroscopy, which may cause excessive radiation losses during upcoming compression experiments. A third chord has been added to the interferometer to measure the line integrated density of the second jet. We present data on the density and magnetic field evolution of the colliding plasmas as well as time-resolved spectroscopic measurements showing that the full 4-jet target system should be able to reach the necessary parameters of density, temperature and embedded magnetic field.