Polymers as Fuel for Laser Plasma Thrusters: Viscous Polymers and Test for Nanoparticles Emission

摘要

This report results from a contract tasking Paul Scherrer Institut as follows: The Grantee will investigate: (A) Ablation of viscous polymers -- Liquid fuels could be used as easy solution to transport sufficient amounts of fuel with a minimum weight of the device. A major issue that has to be controlled is the splashing of the solution during the ablation process, which has been reported to occur during the ablation of liquids. Ns-shadowgraphy measurements on the ablation of viscous polymer solutions will show whether the viscosity has an influence on the splashing behavior shadowgraphy measurements, (B) Test for emission of nanoparticles -- Plasma imaging has shown that the plasma consists of 3 different components which are emitted with different velocities. These different components could be assigned to ions and neutrals (fastest), neutral diatomic species and probably nanoparticles that are emitted at longer time scales (>200 ns). Additional experiments at these longer time scales with spectral resolution will be used to confirm the existence of the nanoparticles. Until now a clear separation of different components in the plume has not been reported for ns irradiation of polymers. It is therefore of great interest to compare the results obtained for femto- and nanosecond laser irradiation especially whether the component separation and nanoparticles emission is only observed for the ultrashort pulses. Additionally, mass spectroscopy measurements should be performed for nanosecond laser irradiation on the same species that have been observed in the plasma emission spectroscopy measurements. (C) Publication of data in peer reviewed journals.