Industrial Microwave Sources at ISM Frequencies

At Forschungszentrum Karlsruhe, Germany, the properties of using millimetre waves for a possible industrial use have been investigated as a spin-off project of the magnetic fusion program and gyrotron development since 1993 [8]. Primarily, the interests have been focused first on processing structural and functional ceramics (like low lossy alumina), where unique advantages of millimetre-wave heating and processing where shown as well as novel system design technologies and hybrid heating. To investigate other industrial applications, e.g. heating or processing organic based materials with microwaves a detailed feasibility study on microwave sources [9], their size and efficiency was performed first. In addition, to understand and predict the material dynamics, hot spot formation, thermal runaway phenomenon etc., several computational codes (MiRa, THESIS, DELFI) developed by the author have been used to clear the choice of internationally licensed ISM (Industrial, Scientific, Medical) frequencies for specific technological applications. Comparing e.g. computationally the properties for applicator design of mm-wave and 2.45 GHz microwave systems, significant differences are noticed as a result of their physical appearance.