Abstract: A microwave applicator including a generally cylindrical microwave containment chamber, a microwave energy source, and a feed structure connecting the microwave energy source to the containment chamber. The diameter of the containment chamber is designed according to a process that need only take into account supporting a microwave pattern having substantially only two transverse magnetic modes, each with a characteristic guide wavelength, where the guide wavelength of one mode is substantially equal to twice the guide wavelength of the other mode. Additionally, the interior diameter can be sized to minimize the index subscript numbers of the transverse magnetic modes. The feed structure of the applicator includes at least two feed apertures spaced physically apart around the cylindrical axis of the applicator by a physical angle equal to an electrical phase shift angle of the microwaves introduced through the respective apertures, which in a preferred embodiment is 90 degrees.

Abstract: A method and apparatus for determining carbon content in fly ash providing a source of fly ash and a microwave interrogation chamber. A quantity of fly ash is introduced into the interrogation chamber and exposed to microwave energy. The amount of carbon in the fly ash is determined by measuring the amount of microwave energy exposed to the fly ash, the amount of energy transmitted through the fly ash, and the amount reflected therefrom in order to determine the amount of energy absorbed. The concentration of fly ash is preferably determined by determining the weight of the fly ash and determining the percentage of carbon content in the fly ash. The method is particularly useful in respect of monitoring carbon content in fly ash of boiler exhaust gases. The system may also be employed to determine the fly ash glass content of fly ash.

Abstract: A microwave oven including a window portion in each of two opposing side walls through which microwave energy is fed into the oven cavity. The window portions are covered by a microwave transparent panel which is configured to support a shelf within the oven cavity.