Direct Observation and Control of Liquid Sodium Flow Dynamics Using VUV-LIF-PIV Technique Under EXB Lorentz Force

Based on a heuristic hypothesis that alkaline metals with one single electron on the outermost shell would little interact with externally applied RF field above plasma frequency, a rudimentary experiment as well as the theoretical estimate of the energy structure been performed to further explore the spectroscopic properties of liquid sodium (Na)^[1–3]. Consequently, it was successfully proven that Na is reasonably transparent to the VUV (vacuum ultraviolet) laser radiation, although the liquid Na surface is highly reflective, being like a mirror to human eyes. The impact of this result is that the velocity field information inside the liquid Na can be visualized by implementing the well developed PIV (particle image velocimetry) technique^{[4, 5]}. A large eddy simulation (LES) code has also been developed for comparison with the experimental results^[6]. Furthermore, the newly developed Na loop is designed so as to enable the application of electric and magnetic field in the orthogonal direction to each other that vigorous dynamics of vortices inside the liquid Na are resolved in the phase space under the Lorentz force. The results herein obtained contribute not only to the thermal hydraulics in fast reactors^{[7, 8]} but also space physics, such as the spiral galaxy formation^[9] and solar flare activities^[10].