Untersuchung des Strahlungsdrucks auf dünne Folien unter Weltraumbedingungen

Kurzfassung

Photons of electromagnetic radiation transfer their momentum on bodies; an ideally reflecting surface doubles the value of the momentum. Thus, a force is acting on the radiated surface of that body. The value of this radiation pressure is rather small, but under special condition, like use in exhausted outer space, there is real effective range of application. The initial point of this thesis is the application of radiation pressure as space propulsion. Large areas of reflective thin films can use the solar radiation pressure for a special type of propulsion in spacecraft applications like the so-called solar sails. The object of this thesis is to develop a measuring facility for analysis the acting force on thin reflective foils by solar like radiation. Furthermore, the facility will be verified by series of measurements, occurring effects will be characterized. This measuring system will be built up and operate in a vacuum chamber. A 1600W Xenon lamp with an AM0 spectrum will illuminate a 7.5 µm thick kapton foil coated with aluminum. A high precision balance measures the acting force on foil surface. In different measurement sequences foil samples are irradiated at different energy fluxes. The measured values correspond to the theoretical value of radiation pressure. Also, in the experiment appears a so far disregarded effect. Under atmosphere and still in vacuum water molecules adhere to the foil surface. These molecules desorb due to first strike of the radiation. The momentum by desorbing molecules is much higher than the momentum of photons. This influence affects radiation pressure measurement. Therefore, relevant boundary conditions are defined in a test procedure to eliminate disturbing influences.