Microwave heating apparatus for laboratory analyses

Claim 1

An analytical microwave apparatus that is especially suitable for laboratory heatings to digest or dry small analytical samples, which comprises a chamber, which retains microwave radiation therein except for that which exits back out through an opening in the chamber which is an entrance for such radiation, which chamber is devoid of any microwave absorbent material except for any analytical samples being heated, a magnetron located outside of such chamber, a wave guide located between the chamber and the magnetron and communicating them through the chamber opening, an isolator, comprising a magnetic shape in the wave guide, and a dummy load and a heat sink, in combination, external to such wave guide, which dummy load absorbs any microwave radiation that exits from the chamber through the wave guide, a first fan or blower for directing air past the heat sink to cool it, so that the air can cool the heat sink continuously over long time periods when the magnetron is operating at full power and there are no analytical samples in the chamber, mechanical radiation mixing means for dispersing throughout the chamber microwave radiation entering the chamber from the wave guide, a second fan or blower, of variable speed capability, for cooling the chamber by drawing air through it, and for removing from the chamber any volatiles that may be generated by the analytical samples during heating thereof, a turntable for moving analytical samples in the chamber while they are being subjected to microwave radiation therein, and programmable means for controlling power input to the magnetron and the duration of such power input, so that the analytical samples may be safely and effectively heated to digest or dry them without damaging the magnetron and without allowing escaping of microwave radiation from the analytical microwave apparatus.