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International audience; Dedicated experimental facilities have been developed at ONERA and CNES (Toulouse, France) for the electrical qualification of space used materials and the extraction of the different physical parameters steering their charging behaviour under electron irradiation.These facilities allow working in a large energy range between few eV up to several MeV, a large temperature range (down to -150°C and up to 600°C depending on the facility) and at high vacuum level. This paper aims at presenting the technical characteristics of these different facilities.

International audience; Implementation of electrical propulsion on new generation satellites involves development of high voltage solar arrays which supposes to solve some technological problems. One of these problems is the interaction between the solar panel and the environment knowing that this environment is modified by the plasma created by electrical propulsion.Concurrently to a numerical approach conducted with SPIS computations, presented in a dedicated presentation, we have carried out an experimental work in order to validate these simulation results.Tests are performed in JONAS plasma facility on a semi-solar panel sizing 4x1m².The solar panel is polarized up to Vbus = 350V to simulate the voltage generated by lightened solar cells. All the electrical setup and solar panel are kept electrically floating versus the chamber walls. Two electrical layouts of solar cell strings are studied with 3 plasma densities from 10e11 to 10e13m-3.For each electrical layout, plasma density and Vbus value, we measure the floating potential of the solar panel and the collected plasma current by solar cells strings.

International audience; Solar panel are key but sensitive elements of spacecraft that produce the spacecraft energy, but are also interacting with the environment, collecting and re-emitting large currents and playing a primary role in the charge state of the whole spacecraft. The different electrical properties of the different materials and the potential bias between the solar cells leads to large potential differences between different elements that may be only separated by a few tens of microns. This generates a risk of potentially destructive electrostatic discharges that can so far only be assessed by experimentation in vacuum chambers. We developed an analytical model of particle collection by small scale elements that is integrated in the large scale simulations of the spacecraft performed by the SPIS software.

International audience; We crossed all the experiments made over 15 years at ONERA during CNES R&D activities; we made hundreds of secondary arcing on Solar Panels or coupons, connectors, SADM1 or simple aged cracked wires. Thanks to the knowledge we have, from ESD2 or secondary arc triggering, to the analysis of in-flight anomalies; we deduct very simple design rules reducing drastically the probability of secondary arcing.Let’s follow the trail of the power line to find where there would be protection gaps.

International audience; Space environment exposure may create cracks on solar panel backside wires. Considering the wiring design of solar array backside, environmental constraints applied on each wire are identical. Thus, the probability of two adjacent wires to have cracks facing each other is very high. This configuration presents a risk of secondary arc occurrence which can lead to a destructive process as arc-tracking. In order to determine in which conditions electrostatic discharges (ESD) can lead to an arc, we have carried out an experimental study on solar panel backside-like samples.We have tested different types of wires presenting artificial mechanical cracks or space simulation aging cracks, set on a solar panel backside coupon.The wires are connected to a secondary arc test setup including a solar array simulator (SAS) set to different current values.As both direct and inverted potential gradient (IPG) charging are theoretically possible on geostationary orbit (GEO) and low earth orbit (LEO), we have carried out, in the JONAS vacuum chamber (ONERA facility), both charging types. Direct charging was achieved with an electron gun and IPG with a plasma source.Results are presented for the two types of charging, different types of wire, and different SAS current values. They show that, in direct charging conditions, ESD propagates along the wires but the plasma density is too weak to provoke an arc. In IPG situation, ESDs are able to trigger different arc types: non-sustain arc (NSA), temporary sustain arc (TSA) and permanent sustain arc (PSA), depending on SAS current values.

International audience; Dedicated experimental facilities have been developed at ONERA and CNES (Toulouse, France) for the electrical qualification of space used materials and the extraction of the different physical parameters steering their charging behaviour under electron irradiation. These facilities allow working in a large energy range between few eV up to several MeV, a large temperature range (down to -150°C and up to 600°C depending on the facility) and at high vacuum level. This paper aims at presenting the technical characteristics of these different facilities.

International audience; As the main activity of the ESA EMAGS3 study (published at 12th SCTC Kitakyushu, Japan) in orbit elec-trostatic discharge, called flash-over, has been simulated on a flight representative panel of dimensions 2 by 4 meters in an environment to achieve inverted gradient conditions on the solar cells. Although not planned within the said study, electrical performance was measured after the panel has suffered from virtually hundreds of flash-over, some of them covering the whole surface. Comparison with the last measurements before testing revealed no degradation beyond measurement error. Obvious differences could be attributed to differences in the circuit. Accompanying experiments on single cells fully support this observation.

International audience; BETs is a three-year Project financed by the Space Program of the European Commission, aimed at developing an efficient deorbit system that could be carried on board any future satellite launched into Low Earth Orbit. The previous measurements and simulations have permitted to show the effect of the orbital velocity on the current collection law. In this paper, new experiments of current collection by a tether are proposed in order to assess the effects of the magnetic field and considering a tape shape instead of a wire. The experiments show that the currents measured never exceed current density predicted by the OML theory. But, it has been shown that, in some case, to use the OML theory leads to a significant overestimation of the current collected. Thermal issues due to the current collection have been observed and quantified. A detailed estimation of the deviation measured in experiments will provide the margins to take in the system integration of the tether.

International audience; Effects of the temperature and the incident electron current density on the total electron emission yield (TEEY) of polycrystalline diamond deposited by chemical vapor deposition technique (CVD) were investigated at low electron beam fluence. It was found that the TEEY reversibly increases with the temperature and reversibly decreases with the current density. This behavior is explained on the basis of a dynamic completion between the holes accumulation which (positive space charge) that internally diminish the secondary electron (SE) emission and the thermally activated conductivity that tends to reduce the space charge formation.