Diagnostics for liquid metal (LM) characterization C. C Tsai, S. W. Allison, M. R. Cates, E. T. Manneschmidt, M. M. Menon, and B. Nelson Oak Ridge National Laboratory, Oak Ridge, TN 37831 Diagnostics are needed for liquid flow experiments for Chamber Technology Research Area. • Develop techniques to measure flow characteristics. – Flow velocity. – Flow thickness. – Flow instabilities. • Measure the thermal response of LM under high heat flux conditions. – Temperature profiles. – Temperature equilibration time after high heat flux pulse loads. • Estimating pumping characteristics of liquid is important prior to introducing LM test modules in major fusion experiments such as NSTX. – Pumping of room temperature hydrogen/deuterium gas – Pumping of energetic hydrogen particles Two novel diagnostics will be developed for LM characterization. • A frequency modulated (FM) coherent laser radar (CLR), utilizing Doppler effect, will be utilized for non-intrusive measurement of LM flow characteristics. – Flow velocity – Flow film thickness – Flow instabilities • Fluorescent phosphor thermometry for measurement of LM temperature – Temperature profile – Temperature equilibration times under high heat flux loading. The FM CLR would be very useful for LM flow characterization • Truly remote measurements using Doppler effect: – Flow velocity distribution – Film thickness distribution Window – Flow instabilities (slow time scale) V • v = f. CLR Laser beam Where, v is the velocity component of Flowing liquid surface the flow in the beam direction, and is the laser wavelength, and fis the Doppler shift in frequency. • By increasing the angle of incidence of the laser beam, the measurable velocity range can be extended. Fluorescent phosphor thermometry can be used for non- contact measurements of LM surface temperature • The technique involves dusting LM surface with special phosphor powder, exciting the phosphor with UV laser, and measuring the fluorescence characteristics using a photomultiplier tube. • The florescence decay characteristic is a measure of the temperature. • The technique can be used to measure surface temperature distribution as well as thermal equilibration time after pulsed heat input. Phosphor Thermometry for Liquid Gallium Drop Fluorescence decay characteristics of a phosphor in liquid gallium surface at two different temperatures • The response is very fast (~ 10µs) • Temperature resolution of few degrees is attainable Fluorescence decay characteristics of a phosphor in liquid gallium surface at different temperatures Preliminary Results Of Phosphor Thermometry Are Encouraging • We have done preliminary compatibility tests of phosphor on liquid Ga and liquid Li • We are preparing to do additional PT tests on static Li. • PT tests on a circulating liquid metal or conducting liquid will be pursued this year. • The design and fabrication of a LM module with an EM pumping will be initiated this year. Summary • Two diagnostics are proposed for liquid wall research – FM coherent laser rada – Phosphor Thermometry • Tests are planned to develop these methods: – Temperature tests on static liquid – Temperature and flow characteristic tests on moving liquid.