MEASUREMENTS OF THE THERMAL RADIATIVE PROPERTIES OF LIQUID URANIUM

Measurements of the thermal radiative properties of liquid uranium hav e been made using an instrument with two optical systems, one for meas uring the complex index of refraction by ellipsometry, the other for m easuring the normal spectral emissivity by direct comparison to an int egral blackbody cavity. The measurements cover the wavelength range 0. 4-10 mum with sample temperatures between 1410 and 1630 K. Two 5-KeV i on sputter guns and an Auger spectrometer produce and verify, in situ, atomically pure sample surfaces. Good agreement between the two metho ds is observed for the normal spectral emissivity, which varies with w avelength in a manner typical of transition metals. The two components of the complex index of refraction-the index of refraction and the ex tinction coefficient-increase with wavelength, from approximately 3 at 0.4 mum to approximately 20 at 9.5 mum. Both components of polarized reflectivity are shown for visible to infrared wavelengths.