A new single mode applicator has been designed and fabricated to provide effective and nearly uniform heating of long ceramic tubes or rods at 2.45 GHz. The applicator is made of two double mitered waveguide corners. A comparison between the new cavity and a rectangular cavity has been carried out to heat various ceramic samples. Results show a significant improvement in the heating rate as well as the reduction of the power needed to attain a given temperature. This paper describes the preliminary test results of the new cavity and the potential to achieve joining of long tubes or rods.