Résumé:

It has been predicted theoretically that for distances smaller than the peak wavelength of the blackbody spectrum, radiative heat transfer can be increased by the contribution of evanescent waves [1]. These effects have already been observed but a quantitative comparison is still missing. We measure the heat flux between a sphere and a plate as a function of the sphere-plate distance. We find a good agreement between the experimental and theoretical results . Particularly, the distance dependence is well reproduced by the theory in a large range of gap widths: 50nm-2μm.