1. Spatial thermal uniformity

1.1 Uniform heat treatment

When using dielectric hysteresis, the appearance of rapid heating and high thermal efficiency, resulting from the concentration of most of the energy within the materials, is deceived by the energy balance. The higher the electromagnetic power degraded into heat, the faster the temperature rise, of course. This first appearance comes from the use, for over sixty years now, of "microwave ovens", usually in the kilowatt range and used to raise the temperature by around fifty degrees, of quantities of foodstuffs of the order of 0.1 kg. The duration of such operations is of the order of a minute, i.e. a temperature increment of the order of 1 K · s ^–1 , even with a poor efficiency of the order of 0.35. The power density...