Speaker
Description
There is a rapidly growing interest in operating satellites in very low Earth orbits (VLEO, $200$-$450$ km). These orbits support efficient communication and Earth observation and offer short post-mission lifetimes due to rapid reentry, reducing the risk of orbit contamination compared to conventional LEO ($>500$ km). The environment is dominated by atomic oxygen, and atmospheric drag and erosion remain primary challenges. At the same time, the residual atmosphere can be used for propulsion and lift. Experimental validation of appropriate concepts requires ground-based facilities reproducing VLEO conditions: neutral atomic oxygen fluxes with a kinetic energy of around $5$ eV and a density of around $10^{9}\,\mathrm{cm^{-3}}$.
This work presents a new test facility design based on a negative oxygen ion beam. An RF plasma source initially generates $\mathrm{O_2^-}$ and $\mathrm{O^-}$ ions in the keV range, which are either magnetically filtered using a dipole magnet or velocity filtered in an $E \times B$ field (Wien filter) to obtain pure $\mathrm{O^-}$. The beam is then decelerated to target energies using an ion-optical system designed to minimize divergence under space-charge effects. Immediate downstream neutralization is achieved via laser photodetachment, enabling contactless conversion without momentum transfer. Residual ions are removed magnetically.
The development work presented focuses on the deceleration unit, ensuring low-divergence beam transport at high currents. Configurations such as ring electrodes, resistive tubes, and combined electrode-grid systems were studied, including aperture control. The design process is supported by numerical simulations of the individual components, carried out using the PICLas code, which enables self-consistent modelling of space-charge effects. Using this approach, a configuration has been developed that meets the defined requirements, demonstrating the feasibility of the proposed concept.
| Email address | voigtl@irs.uni-stuttgart.de |
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| Funding Agency | Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project-ID 5162386 |