Evaluation of electron-emitting film for spacecraft charging mitigation (ELFs charm)

To protect the satellite from the accidents due to spacecraft charging, Kyushu Institute of Technology (Kyutech) is developing a device called ELFs-Charm, which stands for ELectron-emitting Film for Spacecraft CHARging Mitigation. ELFs-Charm was mounted on HORYU-II, which was launched to a Polar Earth Orbit in May 2012. From the orbital data, the emitter’s soundness and working principles were confirmed. As a next step, we are considering the practical operation for mitigation of spacecraft charging. The present emission level was not enough to increase the satellite potential. Theoretically, if the emitter can emit more electrons than the incoming electrons, it can increase the satellite potential during the sub-storm. We focus our efforts on improving two parameters. One is the potential difference of the emitter surface. Another one is the threshold voltage of electron emission. A potential difference of the emitter surface depends on the insulator charging capacity due to the secondary electron emissions with each energy gap between the satellite potential and the primary electron energy. The threshold voltage depends on the shape of emitter. We can improve the ELFs-charm emission performance by measurement of these two parameters in ONERA Space Environment vacuum chamber and Kyutech Space Environment chamber. In this paper, we describe the two parameters of several samples and how the performance was improved.The 31st International Symposium on Space Technology and Science (31st ISTS), June 3-9, 2017, Matsuyama, Japa

Modélisation et simulation numérique de la génération de plasma dans les décharges couronnes et de son interaction avec l'aérodynamique

Des études antérieures ont montré la possibilité d agir sur des écoulements d air subsoniques par l'intermédiaire d'actionneurs électriques générant le phénomène du vent ionique. Des mesures indiquent des gains de vitesse de quelques mètres par seconde. Ces actionneurs ne nécessitent ni apport supplémentaire de masse, ni pièce mobile et peuvent être utilisés sur une très large gamme de fréquences. Le but de cette thèse est de modéliser et de développer un outil numérique capable de simuler la génération de plasma dans les de charges couronnes et son interaction avec l'aérodynamique. La con guration étudiée est composée de deux électrodes laires posées ou incrustées sur une plaque diélectrique et portées à de forts potentiels positifs et/ou négatifs. Grâce à un modèle physique et numérique, le développement de la décharge est simulé en géométries pseudo 1D et 2D. Une étude paramétrique poussée montre une interaction forte entre les deux zones de création du gaz ionisé, situées près des électrodes. L'action sur l'aérodynamique s explique par le transport des particules chargées dû au champ électrique et leur collision avec les molécules neutres de l'écoulement. Un modèle de couplage des phénomènes électriques et aérodynamiques aboutit à la simulation du vent ionique. L'effet des actionneurs obtenu est en accord avec des mesures effectuées en parallèle de cette thèse.TOULOUSE-ISAE (315552318) / SudocSudocFranceF

Characterization of Jason-3 Spacecraft Surface Charging in LEO Polar Regions From AMBER Observations

International audienceWe have characterized spacecraft charging events in low Earth orbit (LEO) polar regions with the Active Monitor Box of Electrostatic Risk (AMBER) instrument onboard the Joint Altimetry Satellite Oceanography Network-3 (Jason-3) ocean topography mission for the first time for this spacecraft. AMBER data, taken at an altitude of 1336 km, over the period January 2017-March 2020, with measurements recorded close to the current solar minimum have been analyzed, using systematic filtering of ions spectrograms with selected threshold energies and time windows to detect negative spacecraft charging events; 109 spacecraft charging events were found. The events are examined visually and characterized by their spatial and temporal location, duration, and intensity (e.g., spacecraft potential). At the Jason-3 altitude (1336 km), the ion signature predominately lasts under 30 s in conjunction with auroral inverted V crossings, while intense fluxes of electrons corresponding to the encounter of the discrete auroral region last between 30 s and 1 min. Most of the detected spacecraft charging events show charging levels between −30 and −1000 V. The spacecraft charging events are located in the magnetic local time (MLT) sector 17h-05h, predominately before midnight. The distribution is equal between the northern and southern hemispheres. We found a high correlation between the charging time profile and that of the auroral electron average energy and energy flux along the satellite path. Overall statistics over three years as well as different event morphologies, electron spectra, and comparisons to worst case electron flux spectral distributions are presented and discussed

Simulation of the Potential of a CubeSat designed for Accurate Plasma Measurement in LEO

International audience

Evaluation of Electron-Emitting Film for Spacecraft Charging Mitigation (ELFs Charm)

To protect a satellite from accidents due to spacecraft charging, Kyushu Institute of Technology (Kyutech) is developing a device called ELFs-Charm, which stands for ELectron-emitting Film for Spacecraft CHARging Mitigation. Electron emission from ELFs-Charm was already confirmed in Polar Earth Orbit in 2012 via flight experiment onboard HORYU-II. As a next step, we are considering the practical operation for spacecraft charging mitigation. The present emission level is not enough to increase the satellite potential. We focus our efforts on improving two properties, charging property and the emission threshold. The charging property is measured by how well the differential voltage between the ELFs-charm insulator surface and the satellite chassis increases. The emission threshold is measured by the differential voltage when the electron emission starts. This paper reports the laboratory experimental results to measure the two properties of various samples. The sample made of fluorin resin coating had a good combination of the charging property and the emission threshold that makes it possible to emit electron under realistic ambient electron current density in orbit.The 31st International Symposium on Space Technology and Science (ISTS), June 3-9, 2017, Matsuyama, Japa

Modelisation elementaire du vent ionique dans une decharge couronne

Communication to : 4eme conference de la Societe francaise d'electrostatique, Poitiers (France), 2-3 septembre 2004SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.2004 n.133 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

A Study of Solar Orbiter Spacecraft–Plasma Interactions Effects on Electric Field and Particle Measurements

International audienceWe present numerical simulations of the Solar Orbiter spacecraft (SC)/plasma interaction performed with the SC–plasma interaction system software. Solar orbiter, to be launched in 2019, is dedicated to observe the sun and the solar wind. The SC will be equipped with both in situ and remote sensing instruments and will approach the sun as close as 0.28 AU. The whole SC will be subjected to an intense electromagnetic radiation flux (ten times that at the earth) leading to specific thermal and SC–plasma interactions issues. This paper investigates plasma interaction effects with two instruments: the radio and plasma waves and the electron analyzer system