Engineering topics
Hwang, David
Publications and source records attributed to Hwang, David.
Thermocouple-tip-exposing temperature assessment technique for evaluating photothermal conversion efficiency of plasmonic nanoparticles at low laser power density
A new thermocouple (TC) tip-exposing temperature assessment technique that combines experimental temperature measurements with a numerical model of the photothermal conversion efficiency η is presented. The proposed technique is designed to evaluate η for a gold-coated superparamagnetic iron oxide nanoparticle (SPIO-Au NP) solution (26 nm, 12–70 ppm) at low continuous wave laser power (103 mW, 532 nm) irradiation in a convenient manner under ambient conditions. The TC tip temperature is measured during the first 30 s of the laser exposure, and the results are combined with a finite element model to simulate the temperature rise of the NP solution for a given concentration. The value of η is adjusted in the model until the model agrees with the measured transient TC temperature rise. Values of η = 1.00 were observed for all concentrations. Theoretical predictions of η derived by Mie theory confirmed the near unity conversion efficiency of the as-synthesized SPIO-Au NPs. Advantages of the current technique include co-locating the TC tip in the geometric center of the laser-heated region, rather than outside of this region. In addition, the technique can be done under ambient room conditions using unmodified commercially available hardware.
Formation of Dense Magnetized Plasmas via Laser Generated Beat Wave Current Drive
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