Microwave oven equipped with a microwave generating apparatus designed to reduce secondary electron emission

A microwave oven incorporating therein a cooking chamber, a waveguide, and an apparatus for generating a microwave, the apparatus comprising:

• a heating-element;
• a cathode, mounted above the heating element, for emitting electrons;
• a first grid, provided above the cathode, for controlling and focusing the flow of electrons emitted from the cathode, the first grid having a plurality of holes for converting electrons from the cathode to the electron beams and, a first secondary electron reduction means for reducing emission of secondary electrons from the first grid, the first secondary electron reduction means mounted on a surface of the first grid facing the cathode;
• a choke structure, positioned between the cathode and the first grid, for serving as a blocking capacitor;
• wherein the cathode, the first grid and the choke structure define an input cavity functioning as a resonant circuit;
• a resistor, one end of which is connected to the first grid and the other end thereof is connected to the cathode, for inducing a bias voltage on the first grid;
• a second grid provided above the first grid and having a plurality of holes through which the electron beams passing through the holes of the first grid pass;
• an anode for receiving the electrons passing through the holes of the second grid, the anode having a second secondary electron reduction means for reducing emission of secondary electrons from the anode in a way of changing a direction of electrons heading for said anode, the secondary electron reduction means mounted on a surface of the anode facing the second grid, wherein the second grid and the anode define an output cavity for generating a microwave, the output cavity being electrically insulated from the input cavity, cooling fins, provided around the anode, for cooling heat generated by the anode;
• a driving voltage source for providing a driving voltage to the cathode and the anode, an antenna arranged in the anode, for extracting the microwave from the output cavity into the cooling chamber through the waveguide;
• and
• a feedback structure extending from the input cavity to the output cavity, for feeding a portion of the microwave in the output cavity back to the input cavity.