Cryogenic apparatus for study of near-field heat transfer

TitleCryogenic apparatus for study of near-field heat transfer
Publication TypeJournal Article
Year of Publication2011
AuthorsKralik, T. - Hanzelka, P. - Musilova, V. - Srnka, A. - Zobač, M.
Date Published05/2011

{For bodies spaced in vacuum at distances shorter than the wavelength of the thermal radiation, radiative heat transfer substantially increases due to the contribution of evanescent electromagnetic waves. Experimental data on heat transfer in near-field regime are scarce. We have designed a cryogenic apparatus for the study of heat transfer over microscopic distances between metallic and non-metallic surfaces. Using a mechanical positioning system, a planeparallel gap between the samples, concentric disks, each 35 mm in diameter, is set and varied from 10(0) to 10(3) mu m. The heat transferred from the hot (10 – 100 K) to the cold sample (similar to 5 K) sinks into a liquid helium bath through a thermal resistor, serving as a heat flux meter. Transferred heat power within similar to 2 nW/cm(2) and similar to 30 mu W/cm(2) is derived from the temperature drop along the thermal resistor. For tungsten samples, the distance of the near-field effect onset was inversely proportional to temperature and the heat power increase was observed up to three orders of magnitude greater than the power of far-field radiative heat transfer. © 2011 American Institute of Physics. {[}doi:10.1063/1­.3585985]}