Abstract: There is described a hybrid furnace comprising a microwave source, and an enclosure for the confinement of both microwave and RF energy for containing an object to be heated. The microwave source is coupled to the enclosure. The furnace further includes an RF source coupled to the enclosure, and a controller for controlling the quantity of microwave energy and RF energy to which the object to be heated is exposed. There is also described a method of operating a furnace of the above type to the heat an object. The microwave source is actuated to induce an electric field to heat the object and the RF source is controlled to selectively provide an oscillating electric field within the object to be heated at a location at a temperature where the field strength of the microwave-induced electric field falls below a predetermined threshold value.

Abstract: There is described a hybrid furnace comprising a microwave source, an enclosure for the confinement of both microwave and RF energy and for containing an object to be heated, and means for coupling the microwave source to the enclosure. The furnace further comprises an RF source, means for coupling the RF source to the enclosure, and a control means for controlling the quantity of microwave energy and RF energy to which the object to be heated is exposed. There is also described a method of operating a furnace of the above type comprising the steps of actuating the microwave source to heat the object and actuating the RF source to provide an oscillating electric field within the object to be heated at a location and/or at a temperature where the field strength of the microwave-induced electric field falls below a predetermined threshold value.

Abstract: A microwave furnace (10) of the type comprising a microwave source (14), coupled to an enclosure for the confinement of microwaves and for containing an object to be heated (12). An independently controllable alternate heating (20) is disposed in relation to the enclosure (12) to provide at least one of radiant and convective heating within the enclosure. The method comprises the steps of energizing the alternate heater (20) so as to generate heat substantially throughout the heating cycle of the furnace (10) and controlling the quanity of heat generated in the object y one or both of the microwaves and the alternate heater so as to provide a desired thermal profile in the object. A temperature sensor to measure the ambient temperature within the enclosure (12) can be provided and control circuit (54) responsive to the sensed temperature controls the quanity of heat generated in the object by the microwaves and the alternate heat so as to provide a desired thermal profile within the object.