Laser flash thermal diffusivity determination procedure for high temperature liquid metals
Murphy, Jennifer Ann
Master of Science
A method is proposed for determining the thermal diffusivity of high temperature liquid metals that involves levitating a small sample under microgravity conditions, melting it, and predicting its thermal response to a laser pulse from either side at time t = 0. The solution is obtained by determining the initial temperature distribution in the thermal penetration depth created by the laser pulses and then solving the two dimensional conduction equation in spherical coordinates for the cooling history of the droplet. The correct diffusivity is obtained by minimizing the difference between predicted temperatures and experimentally obtained temperatures. The method is demonstrated for nickel, iron, and copper, and is shown to have good accuracy. An error analysis reveals that the result is highly sensitive to bias error in the experimental temperature data, and an example is given in which order of magnitude estimates for diffusivity can be obtained from the curves provided.