Propriétés Electriques d'Environnements Ionisés

Mon activité scientifique consacrée aux études des propriétés électriques d'environnements ionisés s'est répartie entre théorie, modélisation et interprétation de résultats expérimentaux, avec le souci constant de bien maîtriser le fonctionnement des instruments de mesure utilisés.Cinq thèmes principaux ont été développés au cours des dernières années : Instruments de mesure: concept, modélisation, interprétation dans le plasma magnétosphérique (dans le plasma ionosphérique, dans l'atmosphère et dans les tornades de poussières), Impact des orages magnétosphériques sur l'atmosphère/ionosphère, "Chauffage" de l'ionosphère par les ondes HF, chargement électrique des poussières atmosphériques, décharges électriques dans l'atmosphère: mécanismes, impact sur l'ionosphère et l'atmosphère.En 2014-2020 mes efforts, ainsi que les efforts de mon équipe, seront principalementconcentrés sur deux sujets, i.e. le chargement électrique des poussières et les déchargesélectriques dans l'atmosphère. Tous les deux sont motivés par les expériences spatiales encours de préparation, i.e. atterrisseurs martiens et lunaires avec un « package » d'instrumentspour mesurer les poussières et le microsatellite TARANIS comportant un ensembled'instruments de mesure du champ électrique et des ions thermiques dans l'ionosphèreterrestre

Reconstruction of the ion plasma parameters from the current measurements: Mathematical tool

Instrument d’Analyse du Plasma (IAP) is one of the instruments of the newly prepared ionospheric mission Demeter. This analyser was developed to measure flows of thermal ions at the altitude of ~ 750 km and consists of two parts: (i) retarding potential analyser (APR), which is utilised to measure the energy distribution of the ion plasma along the sensor look direction, and (ii) velocity direction analyser (ADV), which is used to measure the arrival angle of the ion flow with respect to the analyser axis. The necessity to obtain quick and precise estimates of the ion plasma parameters has prompted us to revise the existing mathematical tool and to investigate different instrumental limitations, such as (i) finite angular aperture, (ii) grid transparency, (iii) potential depression in the space between the grid wires, (iv) losses of ions during their passage between the entrance diaphragm and the collector. Simple analytical expressions are found to fit the currents, which are measured by the APR and ADV collectors, and show a very good agreement with the numerical solutions. It was proven that the fitting of the current with the model functions gives a possibility to properly resolve even minor ion concentrations and to find the arrival angles of the ion flow in the multi-species plasma. The discussion is illustrated by an analysis of the instrument response in the ionospheric conditions which are predicted by the International Reference Ionosphere (IRI) model

EF-ATLEC multi-instruments gondola

EF-ATLEC multi-instruments gondola for balloon flights in stratosphere in conjunction with satellite TARANIS mission" MG & ES /LATMOS In frame of preparation of TARANIS mission (CNES micro-satellite; launch: ~2015; geosynchronous orbit at ~700 km) we are developing multi-instruments gondola for the CNES balloon flights in equatorial, mid-latitude stratosphere. The idea is to carry in-situ observations of lightning and associated stratospheric discharges (TLEs blue jets, elves, etc.) simultaneously and in conjunction with the satellite observations in the ionosphere. For this purpose we are developing a multi-instruments autonomous gondola for the balloon flights with low power instruments that required high data rate acquisition and accurate dating. The LATMOS EF-ATLEC gondola consists of the electric field instrument SDA (DC-few kHz), photometers, 3D cameras, sound recorder. The concept of this gondola is planned to be used by other high data rate instruments on Cobrat/Taranis balloon project, like search-coil magnetometers and gamma detector. Preliminary tests of multi-instruments gondola with two onboard instruments (SDA of LATMOS and Field Mill of SPRL/Michigan) were performed in 2011 during CNES campaign in Kiruna/Sweden. Results and future developments are discussed

All-sky camera of the ALFA project: common points and interests with the Wide Field Astronomical observations, Wide field imagining at Dôme C.

Video diffusée le 14 jui

Small, Mobile and Autonomous Instrument to Measure Electric Field and Electric Conductivity of Air

International audienceWe have developed a small, mobile and autonomous instrument to measure electric field and electric conductivity of air in different conditions found in the Earth atmosphere. The size of our instrument is determined by the size of the industrial PC-104 board. Other “home-developed” cards (electronic boards of the electric field measuring, power board) have the same format as the PC-104 one. All are stacked in a metallic box together with the Li-ion batteries that insure up to 10 hours of autonomy. Collected data are saved in an internal memory. The electrodes and their booms are accommodated on the box. The box size is 12 × 12 × 20 cm and its weight is 2 kg. Thus, easy to put your backpack to walk till the measurements site

Response of thermal and supra-thermal ionospheric plasma to energy input from magnetosphere and atmosphere during magnetospheric and thunder-storms: Demeter observations

We present and discuss few examples of plasma observations made in ionosphere at ~700 km by CNES micro-satellite Demeter during magnetospheric and thunder-storms. The conjugated observations of onboard ion retarding & drift analysers and electric field antennas (both developed by the LATMOS team) together with remote optical imagers and VLF antennas allow to analyse the perturbations of the plasma parameters (ions composition, drift and field-aligned motion, temperature and density of thermal and suprathermal population) with respect to the variation of the field-aligned currents, the electron and proton precipitation, the power and localisation of electric discharges

Dust lifting experiment (DLE) : variations of electric field and electric resistivity of air caused by dust motion

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What we can learn from the electric field and conductivity measurements in auroral atmosphere

International audienceIn this paper we present measurements of the electric field and electric conductivity of air performed with the Short Dipole Antenna (SDA) in the auroral atmosphere. The observations were carried out during two stratospheric balloon flights in the northern Sweden in winter of 2011. Two‐fold objectives were attained as the outcome of these flights and the data analysis. First aimed at understanding the mechanisms that control the electric properties of the auroral atmosphere and at estimation of some key parameters from the measured data, such as the charge and current density, the mobility of the small‐ions, their concentration and generation rate, as well as the radiation dose rate. Second objective was to test the SDA instrument performances in a radiation environment close to that we expect to encounter near the Mars surface