M.Sc Thesis

M.Sc StudentSister Ilya
SubjectBlackbody Thermal Radiation Calculation Using the Source
Model Technique
DepartmentDepartment of Electrical and Computers Engineering
Supervisors PROF. Levi Schachter
Full Thesis textFull thesis text - English Version


Planck’s famous blackbody radiation (BBR) law was derived under the assumption that the radiating body’s dimensions are significantly larger than the radiated wavelengths.

What is unique about Planck's formula is the fact that it is independent of the exact loss mechanism and the geometry. For this reason for a long period of time, it was regarded as a fundamental property of all materials and deviations from its predictions were attributed to imperfections and defined as the emissivity of the specific body - the former has always been assumed to be smaller than unity.  

Recent studies showed that the emission spectrum is affected by the body’s geometry and in fact, in a limited frequency range the emitted spectrum may exceed Planck's prediction provided the typical size of the body is of the same order of magnitude as the emitted wavelength.  For the investigation of BBR from an arbitrary shape body, we developed a code which combines the Fluctuation-Dissipation Theorem (FDT) to determine the correlation between the quasi-microscopic current densities in the body and the Source Model Technique (SMT) for numerical solution of the electromagnetic problem. In this study we present the essence of combining the two concepts. We compare the numerical results for a sphere with analytic results developed more than four decades ago; the numerical error is quantified independently. Finally, we illustrate several configurations in which the emitted spectrum exceeds Planck's prediction as well as cases whereby the geometrical resonances of the body are revealed.