CAVITY PRESS OPERATING AT A NATURAL FREQUENCY OF THE WORKPIECE

摘要

An apparatus for applying pressure and a high frequency electric field to material, comprising a cavity for containing the electric field which encloses platens relatively movable to apply pressure to material placed between the platens. The cavity electrically communicates with the platens for supplying the contained electric field to the platens which, in turn, cooperate with each other to apply the field to the material between the platens. The cavity and the platens are also directly coupled into the generating circuit which generates the electric field as a resonant circuit. The apparatus includes a triode valve for preventing excessive current therethrough as voltage is first applied. A circuit is also provided for operating the triode under optimum conditions utilizing an automatically variable capacitor to maintain a predetermined grid current for a workpiece placed within the apparatus after full voltage has been applied.