| Radiative heat transfer is one of the fundamental modes of energy transfer between media. The fundamental law underlying radiative heat transfer is Planck's Law, which is an expression relating the maximum emitted energy from a surface at a given wavelength to the temperature of the surface. The fundamental nature of Planck's Law means that any modification of this distribution could be used to enhance or reduce radiative heat transfer from a surface. One of the underlying assumptions of Planck's Law is that the electric field at an emitting surface is zero. Applying a large electric field to the surface, thereby inducing a nonlinear polarization of the surface, could violate this assumption. A flared concentric cylinder blackbody radiation source has been constructed in which a large electric field can be applied to the emitting surfaces to determine if radiative heat transfer can be modified by applied electric fields. A Monte Carlo analysis of this cavity was performed to estimate the emissivity of this source, which provides a measure the effectiveness of the new source as a blackbody radiator. An FTIR spectrometer was then used to acquire spectra from the source with and without an applied electric field, and these spectra are used to characterize the source and to explore the effects of applied electric fields on thermal emissions from surfaces. A theoretical analysis detailing the nonlinear interaction between applied electric fields and material optical properties is then used to explain null experimental results. |
