Structures of microwave tunnel kiln

Summary form only given. The electric field is uniform in the tunnel. The kiln has a blanket with double layer thermal insulation. Varying the thermal insulator can create the temperature gradient. The inner layer is made of mulite base cement. The loss tangent of it is the order of 10/sup -2/ which is equivalent to the work pieces. The microwave reflects on the metallic wall of the tunnel repeatedly and electric field intensity is expected to be uniform in it. The outer layer is thermal insulator made of alumina/silica fiberboard. The thickness of it varied along the axis to increase the temperature of the wall as illustrated.