Far Beyond Small Perturabations

Advantages of single mode resonant applicators at a single frequency, over multimode ovens are examined, particularly for such scientific applications as the heating of liquids, organic chemistry, or sintering and joining of ceramics. It is seen that a knowledge of the spatial distribution of the electric field can be extremely useful in understanding and designing applicators for optimal processing, particularly for applicators which usually violate the small perturbation theory criteria.Numerical modeling of the electromagnetic fields is investigated for a single mode rectangular cavity (TEamp) crossed by a cylindrical tube. This tube is filled with polar liquids such as solvents used in organic chemistry (e.g. water or ethanol)the dilution factor or ratio sample volume (approximately 5 cm3)to cavity volume is close to 10. Solutions for the wave numbers, quality factor, tuned length, and resonant frequency are accomplished by mode-matching techniques. Appropriate field components are matched across the boundary regions to form a characteristic matrix whose complex determinant is zero. The model includes wall losses, and the cavity was always assumed to be tuned at 2.45 GHz. Electric field patterns for water and ethanol for several temperatures and the influence of tube diameter are presented. Numerical results prove that the electric field amplitude inside the lossy sample can greatly differ from the no-loaded cases or expected values of small perturbation theory. An estimating criteria has been proposed to estimate without calculations the electric field amplitude inside the load. Experimental correlations were made with an experimental cavity (TE0715)and experimental results are presented.