Microwaves are a fast way to dry moist goods through volumetric heating. During the drying process, materials change their electrical properties. As a result, the impedances at the feed port of the applicator will change and the microwave source is not matched anymore. The amount of reflected power increases and the process efficiency reduces. New semiconductor high power sources can perform a dynamic impedance matching. A lab scaled functional model with two sources was designed and realized. For measuring the scattering parameters during the process run, an embedded two-port vector network analyzer was added. Measurement results confirm the feasibility of the concept.   Keywords: Microwave drying, dynamic efficiency optimization, multichannel feed, solid state based microwave source

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Earth's upper atmosphere is a dynamic system that is determined by external and internal forces. Understanding this system allows for insights into the evolution of a habitable world and, therefore, the origin of our Solar System. In addition, it is the environment for many satellites that are key to our modern world. The uppermost part of Earth's atmosphere, the exosphere and ionosphere, couples the collision-dominated thermosphere with outer space, where other processes determine the trajectories of the particles. Whereas the thermosphere is mostly gravitationally bound to the planet, a fraction of the particles present in the exosphere leaves Earth into interplanetary space. Over geologic times, these loss processes are an important factor in the evolution of an atmosphere and are considered being the main reason why Earth currently has a habitable atmospheric surface composition in contrast to Venus and Mars, which were all very similar once. In the short term, the variability of the Sun's radiation, including both photons (from XUV to IR) and energetic particles causes considerable variations in the chemical composition, the density, and the spatial extent of the TABLE OF CONTENTS 1. INTRODUCTION .

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