Alain Hilgers

SPIS Open-Source Code: Methods, Capabilities, Achievements, and Prospects

In this paper, recent improvements in the modeling capabilities of the Spacecraft Plasma Interaction Software (SPIS) code are presented. New developments still in progress are also reported. They should in particular allow modeling of fast dynamical phenomena, including processes as challenging as the second part of ESDs, i.e., the vacuum arc and its related flashover plasma expansion. The first, electronic, part of ESDs is already modeled. The range of SPIS application domains and studies is reviewed. An interesting study case, the assessment of charging at multiple-scale levels, is presented here in more detail. Charging in geostationary-Earth-orbit conditions is simulated from the spacecraft scale down to a solar-cell-gap (hence, decameters to millimeter) scale. This self-consistent computation shows that macroscopic inverted-voltage-gradient (IVG) cases may differ at microscopic scales close to a solar-cell gap, due to the local blocking of secondary emission by the small-scale electric-field configuration. We consider this effect as the likely origin of the different ESD triggering thresholds, depending whether IVG is obtained by electrons or plasma.

SEPEM: A tool for statistical modeling the solar energetic particle environment

Solar energetic particle (SEP) events are a serious radiation hazard for spacecraft as well as a severe health risk to humans traveling in space. Indeed, accurate modeling of the SEP environment constitutes a priority requirement for astrophysics and solar system missions and for human exploration in space. The European Space Agencys Solar Energetic Particle Environment Modelling (SEPEM) application server is a World Wide Web interface to a complete set of cross-calibrated data ranging from 1973 to 2013 as well as new SEP engineering models and tools. Both statistical and physical modeling techniques have been included, in order to cover the environment not only at 1 AU but also in the inner heliosphere ranging from 0.2 AU to 1.6 AU using a newly developed physics-based shock-and-particle model to simulate particle flux profiles of gradual SEP events. With SEPEM, SEP peak flux and integrated fluence statistics can be studied, as well as durations of high SEP flux periods. Furthermore, effects tools are also included to allow calculation of single event upset rate and radiation doses for a variety of engineering scenarios.

Modeling of Plasma Probe Interactions With a PIC Code Using an Unstructured Mesh

A new Spacecraft Plasma Interaction Software has been developed in the frame of the Spacecraft Plasma Interaction Network (SPINE). This software is designed to simulate the kinetic processes of ions and electrons, taking into account their space charge and their interaction with spacecraft surfaces. It is freely available worldwide in open source. While the development and the qualification of the software functionalities were under the responsibility of a consortium led by ONERA under contract with the European Space Agency, the test and validation of the applicability of the code for solving problems in plasma physics remained under SPINE responsibility. The validation program includes step-by-step applications of the software to sheath modeling in simple geometry, artificial plasma injection, and spacecraft charging. We report here on the progress along this program, including Langmuir probe tests with spherical and cylindrical geometry and comparison with other numerical methods.

Simulation of the Cluster-Spacecraft Floating Probe Potential

In this paper, a numerical model of the Cluster-spacecraft electric potential has been developed and validated. This model provides a good fit to the plasma density as a function of spacecraft chassis potential relative to a Langmuir probe as recorded along the Cluster-spacecraft orbit when the plasma density was between 1 and 80 cm -3 during a plasmaspheric crossing. The model is used to assess the uncertainty in density-determination methods based on potential measurements. Furthermore, this model provides constraints on the parameters suitable for describing the photoelectron emission and might be used in the future to estimate plasma temperature in space

Cross-comparison of spacecraft-environment interaction model predictions applied to Solar Probe Plus near perihelion

Five spacecraft-plasma models are used to simulate the interaction of a simplified geometry Solar Probe Plus (SPP) satellite with the space environment under representative solar wind conditions ne ...

Simulation Study of Spacecraft Electrostatic Sheath Changes With the Heliocentric Distances From 0.044 to 1 AU

In this paper, the electrostatic sheath of a simplified spacecraft is investigated for heliocentric distances varying from 0.044 to 1 AU, using the 3-D Particle in Cell software Satellite-Plasma Interaction System. The baseline context is the prediction of sheath effects on solar wind measurements for various missions, including the Solar Probe Plus mission (perihelion at 0.044 AU from the sun) and Solar Orbiter (SO) (perihelion at 0.28 AU). The electrostatic sheath and the spacecraft potential could interfere with the low-energy (a few tens of eV) plasma measurements, by biasing the particle distribution functions measured by the detectors. 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 Solar Probe Plus and SO cases will be presented in details and extended to other distances through a parametric study, to investigate the influence of the heliocentric distance to spacecraft. Our main result is that, for our spacecraft model, the floating potential is a few volts positive from 1 AU to about 0.3 AU, while below 0.3 AU, the space charge of the photoelectrons and secondary electrons create a potential barrier that drives the spacecraft potential negative.

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.

SPIS 5: New Modeling Capabilities and Methods for Scientific Missions

Since the last version, the numerical core and the user interface of Spacecraft Plasma Interaction Software (SPIS) have been significantly improved to achieve two objectives: 1) to make SPIS more user friendly and robust for industrial use and 2) to extend the multiscale capabilities and the precision of the solvers in order to model a large range of scientific missions. The new numerical algorithm and modeling capabilities are presented in detail. This new version permits modeling of time variations of the plasma environment, spinning spacecraft, semitransparent grids, secondary emission from 1-D thin elements (e.g., wires or booms), 2-D thin elements (for example, solar arrays), the effect of v × B electric field, particle detectors, and Langmuir probes onboard spacecraft.

Conceptual Design and Assessment of an Electrostatic Discharge and Flashover Detector on Spacecraft Solar Panels

This paper presents a concept of monitor aiming at measuring the electrostatic discharge (ESD) occurrence and, possibly, a flashover expansion on spacecraft photovoltaic solar panels. The passive measurement of solar cell cover glass surface potential is used as a diagnostic. The monitor consists of small metallic plates located on the sunlit solar panel. With a sufficient electrical insulation from the spacecraft structure, these plates float to the same potential as the surrounding cover glasses. The photoemission is the physical phenomenon allowing the homogenization of the local surface potentials. Theoretical, numerical, and experimental investigations are used to assess how well such a device could record the evolution of the solar panel surface voltage. Combined with a dedicated measurement chain and telemetry, ESD occurrences could thus be measured on in-flight solar panels.

Guest Editorial Special Issue on Spacecraft Charging Technology

This issue marks the fifth issue of the IEEE TRANSACTIONS ON PLASMA SCIENCE dedicated to Spacecraft Charging Technology. The theme of this issue is based on the papers presented at the 13th Spacecraft Charging Technology Conference, Pasadena, CA, 2014.