Atmospheric transport and suspension of aerosols frequently lead to substantial electrification in Earth’s atmosphere, within thunderclouds, volcanic ash plumes, and even sandstorms in deserts — lightning being among the most energetic and remarkable manifestations of this electrical activity. On Earth atmospheric electricity has significant implications for dust dynamics, by charging particles in the atmosphere, which can affect the transport of dust. It also plays a critical role in atmospheric chemistry by driving ionisation and facilitating the production of oxidants. The generation of electric fields in such environments arises from charge separation during repeated and intense collisions between particles such as ice crystals, water droplets, ash, or sand grains, namely, triboelectricity. 

Given their ubiquity on Earth, triboelectric processes likely operate in other planetary environments with large dust and sand reservoirs, such as Mars. Indeed, dust in ubiquitous in the Martian atmosphere and dust lifting occurs frequently through saltation, dust devils and large-scale dust storms. Therefore, by analogy to terrestrial aeolian processes leading to dust electrification, triboelectric charging — the exchange of electric charge during grain–grain or grain–surface collisions — is expected to generate electric fields within these dust-laden flows. For decades, models and laboratory experiments have predicted the build-up of electric fields in dust event on Mars, eventually leading to spark discharges due to the low breakdown threshold of the atmosphere (~tens of kV/m on Mars compared to 3 MV/m on Earth at sea level). The interest in characterizing those triboelectric phenomena on Mars stems from the hypothesis that Martian electric fields can affect dust dynamics, a major component of the Martian climate, and enhance the oxidizing capacity of the atmosphere, with detrimental consequences for the preservation of organic molecules at the surface.

The recent detection of electrostatic discharges by the SuperCam instrument onboard NASA’s Perseverance rover has reignited interest in Martian atmospheric electricity. For the first time, in situ evidence has confirmed that triboelectric charging occurs in dust devils and dust storm active fronts, leading small scale electrical discharges. This discovery opens a new era for the study of electrified dust on Mars. However, to assess the global consequences of these discharges it is first necessary to better understand the microphysics of dust grain charging itself. Many fundamental questions remain unanswered: how charge is exchanged during collisions between grains of different size, composition, and roughness; how ambient conditions such as pressure, humidity, and temperature influence these exchanges and how charged particles are subsequently transported and organized by turbulence in the Martian boundary layer. It is essential to bridge these scales, from individual grain interactions to the mesoscale behavior of electrified dust, to better understand the mechanisms that give rise to large-scale electrical phenomena on Mars.

The main objective of the proposed thesis is to study the microphysics of triboelectric charging through a combination of in situ data analysis, experimental, theoretical, and numerical approaches:

- An experimental setup, under Mars atmosphere, will be developed to reproduce the triboelectric charging of grains and measure their individual charges and the energy released in discharges.

- Laboratory experiments on this bench will explore the various parameters likely to influence charge transfer, such as grain size distribution, mineralogical composition, and ambient temperature and pressure.

- On the theoretical side, the mechanisms of charge exchange during grain–grain collisions will be analyzed A numerical model coupling grain collisions with charge transfer dynamics will then be implemented and validated against experimental results.

- Finally, these results will be compared with in situ data collected by the SuperCam instrument onboard Perseverance during the detection of discharges on Mars.

This thesis will open a new field on investigation for Mars atmospheric science. If time allows the selected candidate can tackle other topics linked to the subject such as the transport of charged grains by turbulence and wind. 

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For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse - baptiste.chide@irap.omp.eu

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online before March 13th, 2026 Midnight Paris time!