M.Sc Thesis

M.Sc StudentPeterfreund Zvi
SubjectElectromagnetic Forces in the Vicinity of Edges
DepartmentDepartment of Electrical and Computers Engineering
Supervisors PROF. Levi Schachter
PROFESSOR EMERITUS David Schieber (Deceased)
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


            Converting Electromagnetic (EM) energy into mechanical energy is the basis for vast implementations. Much research has been devoted to the exploitation of these EM forces in order to create excitation controlled devices. A case of growing interest is the researches in the limit of optic wavelengths where it is easier to obtain high accuracy for smaller devices.

While manipulation of neutral particles with propagating EM field configurations are of interest, there are some inherent advantages, when the field is confined to a waveguide or a cavity. Motivated by the fact that in the vicinity of an edge the field, and thus its energy density may diverge whereas the total energy is always finite, in the present study we consider the forces exerted by electromagnetic field on an edge or the force between two adjacent edges. Both the field and the edge are confined in a two-dimensional cavity. The latter configuration is chosen in order to keep the two modes decoupled. Moreover, we aim to develop analytic results and keep the analysis as simple as possible, therefore, we assume that the cavity is made of a perfect conductor. Our first step  is to consider an empty metallic cylindrical cavity with a metallic wedge. We investigate the radiation forces which arise from the excitation of modes at cut-off. As a second example, we consider the same configuration as before except that the edge is made of a lossless dielectric. In the third case of interest two dielectric wedges are considered.

It is shown that by the ability to excite certain modes, the attractive and repulsive azimuthal forces exerted on a dielectric or a metallic wedge, may be utilized to manipulate it. The nature of the forces acting on the walls of the wedge can be of either pressure or tension. It is shown that there exists a unique wedge angle for which the average electromagnetic forces acting on the wedge walls equal zero. Furthermore, for a two wedged cavity there is not a singular critical angle but there exist a couple of angles for which the force changes its sign, and it is shown that a change in the properties of one wedge can change the nature of the forces on the other.