Simulations of the solar orbiter spacecraft interactions with the solar wind: effects on RPW and SWA/EAS measurements

International audienceWe present numerical simulations of the future Solar Orbiter spacecraft/plasma interactions performed with the Spacecraft Plasma Interaction System (SPIS) software. This spacecraft, to be launched in October 2018, is dedicated to the Sun observation with in-situ and remote sensing instruments, brought as close as 0.28 A.U. from our star. In this hot and dense environment, the entire satellite will be submitted to high radiations and temperatures (up to 10 Solar constants). Material responses to environment constraints (heat, U.V. flux, photoemission, secondary electron emission under electron impact – SEEE – or under proton impact - SEEP) might bias the scientific instrument measurements. Our interest is focused on two instruments: the Radio and Plasma Waves (RPW) and the Electron Analyzer System (EAS)

Extension of SPIS to simulate dust electrostatic charging, transport and contamination of lunar probes

A modification of the Spacecraft Plasma Interaction Software has been undertaken under ESA contract 4000107327/12/NL/AK (SPIS-DUST). The primary goal is to provide mission designers with an engineering tool capable of predicting charged dust behavior in a given plasma environment involving a spacecraft / exploration unit in contact with complex topological features at various locations of the Moon’s surface. The tool also aims at facilitating dust contamination diagnostics for sensitive surfaces such as sensors optics, solar panels, thermal interfaces, etc. In this paper, the new user interface and the new numerical solvers developed in the frame of this project is presented. The pre-processing includes the building of a 3D lunar surface from a topology description (i.e. a point list), an interface to position the spacecraft and a merging interface for the spacecraft elements in contact with the lunar surface. Concerning the physical models, the new solvers have been developed in order to model the physics of the ejection of the dust from the soils, the dusts charging and transport in volume and the dust interaction and contamination of the spacecraft. The post-processing includes the standard outputs of SPIS for the electrostatic computation and the plasma plus dedicated instruments for the diagnosis of the dusts. A set of verification test cases are presented in order to demonstrate the new capabilities of this version of SPIS in realistic conditions

New SPIS capabilities to simulate dust electrostatic charging, transport, and contamination of lunar probes

The spacecraft-plasma interaction simulator has been improved to allow for the simulation of lunar and asteroid dust emission, transport, deposition, and interaction with a spacecraft on or close to the lunar surface. The physics of dust charging and of the forces that they are subject to has been carefully implemented in the code. It is both a tool to address the risks faced by lunar probes on the surface and a tool to study the dust transport physics. We hereby present the details of the physics that has been implemented in the code as well as the interface improvements that allow for a user-friendly insertion of the lunar topology and of the lander in the simulation domain. A realistic case is presented that highlights the capabilities of the code as well as some general results about the interaction between a probe and a dusty environment

Study and Simulation of Low Energy Plasma Measurement on Solar Orbiter

International audienceThe flux of particles collected by scientific low energy detectors are sensitive to absolute and differential potentials, and may include both ambient and secondary particles emitted by the spacecraft itself. This work presents numerical models of particle detector behaviour on Solar Orbiter, using the SPIS software. The results presented in this paper show the necessity to take into account the spacecraft plasma interactions at the earlier stage of scientific missions' definition, as well as during measurement interpretation. It demonstrates that electrons emitted in the vicinity of the detectors may be the main contributor to low energy electron measurements pollution

Solar wind plasma interaction with solar probe plus spacecraft

International audience3-D PIC (Particle In Cell) simulations of spacecraft-plasma interactions in the solar wind context of the Solar Probe Plus mission are presented. The SPIS software is used to simulate a simplified probe in the near-Sun environment (at a distance of 0.044 AU or 9.5 RS from the Sun surface). We begin this study with a cross comparison of SPIS with another PIC code, aiming at providing the static potential structure surrounding a spacecraft in a high photoelectron environment. This paper presents then a sensitivity study using generic SPIS capabilities, investigating the role of some physical phenomena and numerical models. It confirms that in the near- sun environment, the Solar Probe Plus spacecraft would rather be negatively charged, despite the high yield of photoemission. This negative potential is explained through the dense sheath of photoelectrons and secondary electrons both emitted with low energies (2-3 eV). Due to this low energy of emission, these particles are not ejected at an infinite distance of the spacecraft and would rather surround it. As involved densities of photoelectrons can reach 106 cm-3 (compared to ambient ions and electrons densities of about 7 × 103 cm-3), those populations affect the surrounding plasma potential generating potential barriers for low energy electrons, leading to high recollection. This charging could interfere with the low energy (up to a few tens of eV) plasma sensors and particle detectors, by biasing the particle distribution functions measured by the instruments. Moreover, if the spacecraft charges to large negative potentials, the problem will be more severe as low energy electrons will not be seen at all. The importance of the modelling requirements in terms of precise prediction of spacecraft potential is also discussed

Extension of SPIS to simulate dust electrostatic charging, transport and contamination of lunar probes

A modification of the Spacecraft Plasma Interaction Software has been undertaken under ESA contract 4000107327/12/NL/AK (SPIS-DUST). The primary goal is to provide mission designers with an engineering tool capable of predicting charged dust behavior in a given plasma environment involving a spacecraft / exploration unit in contact with complex topological features at various locations of the Moon’s surface. The tool also aims at facilitating dust contamination diagnostics for sensitive surfaces such as sensors optics, solar panels, thermal interfaces, etc. In this paper, the new user interface and the new numerical solvers developed in the frame of this project is presented. The pre-processing includes the building of a 3D lunar surface from a topology description (i.e. a point list), an interface to position the spacecraft and a merging interface for the spacecraft elements in contact with the lunar surface. Concerning the physical models, the new solvers have been developed in order to model the physics of the ejection of the dust from the soils, the dusts charging and transport in volume and the dust interaction and contamination of the spacecraft. The post-processing includes the standard outputs of SPIS for the electrostatic computation and the plasma plus dedicated instruments for the diagnosis of the dusts. A set of verification test cases are presented in order to demonstrate the new capabilities of this version of SPIS in realistic conditions

Production of optical waveguide in planar glass substrate fabricated with femtoprint

info:eu-repo/semantics/publishe

Measurements of physical parameters characterizing ESDs on solar cell and correlation between spectral signature and discharge position

International audienceElectrostatic discharges on solar cells are possible cause of dramatic consequences such as secondary arcs responsible of definitive power losses. To cope with these significant implications, different approaches are followed such as design rules reducing voltage between adjacent cells, conductive layers or grouting to try to reduce ESDs triggering. However, ESDs on solar cells cannot be completely avoided and having a good knowledge of their characteristics is essential for prevention, prediction and modelling. In this paper, we describe how the plasma emitted during an electrostatic discharge on solar cell can be analyzed with dynamic tools such as triple probes and time-resolved optical spectroscopy. These techniques are used to obtain results on plasma density and electron temperature that can be compared with outputs from ESDs and flashover propagation models. While time-resolved optical spectroscopy is used on a single point (the point where optical fiber is focused on), triple probe is also used for spatial measurements. With this technique, electron density is measured at several distances from the discharge point providing both temporal and spatial information. In a second time, the optical signature measured by optical spectroscopy is correlated with SEM observations showing the existence of two kinds of triple points at the cell's edge. These two kinds of discharges have different optical signatures showing either elements from the active junction or from the substrate and rear electrode. These discharges are also distinguished by SEM observations and images of cell's edges confirm the previous results. These results show the importance of the silver back electrode and also of the eventual presence of covering glue on the position of the discharge. They provide information for models but let us also imagine possible mitigation methods