Nom de l'entreprise / du laboratoire: GREMI - Groupe de Recherches sur l’Energie des Milieux Ionisés

Application submission exclusively on ADUM → https://adum.fr/as/ed/voirproposition.pl?site=adumR&matricule_prop=70659

In a context where environmental challenges at multiple scales have become major issues, it is urgent to develop innovative and efficient solutions. This PhD project aims to design decarbonization processes based on the use of atmospheric-pressure cold plasmas. These technologies are intended in particular to address pollution remediation needs (soils, water, etc.). They also concern localized surface treatment (functionalization, microelectronics, packaging).
The micro-hollow cathode discharge (MHCD) is a cold plasma source with a micrometric interelectrode distance. The anode and cathode are separated by a thin dielectric layer incorporating a cavity that enables gas injection and plasma ignition. These devices, often arranged in matrices of microcavities spaced by a few tens to hundreds of micrometers, are derived from microelectronics fabrication processes.
At GREMI, MHCD reactors are fabricated on semiconductor substrates structured using masks, allowing fine electrode geometries and strong control of the ionization degree thanks to intense electric fields (>100 kV·cm⁻¹). A major originality lies in their operation in direct current (DC) mode at atmospheric pressure, requiring only a few hundred volts. This power supply mode enables precise power control and energy efficiency compatible with decarbonized energy sources. Experiments in pulsed regime will also be conducted for comparison.
The PhD project aims to optimize the microdevices in terms of geometric, electrical, and mechanical characteristics using advanced cleanroom microfabrication facilities available at GREMI and its partner platforms (CERTeM, Renatech). A significant part of the work will be devoted to cleanroom microfabrication processes in order to develop innovative microdevices. The development of an MHCD-based process requires operation at atmospheric pressure under ambient temperature and humidity conditions. However, the influence of humidity remains poorly documented. A central objective will therefore be to investigate the role of the water molecule as a precursor in mixtures of rare gases, nitrogen, or air. The temporal and morphological behavior of the discharge, plasma–surface interactions, chemical kinetics, and electrical and thermal properties will be analyzed.
Characterization will rely on advanced diagnostic techniques. The reactive chemistry resulting from non-equilibrium plasma processes will be studied using time-resolved emission and absorption spectroscopy. These measurements, combined with electrical diagnostics, will allow the estimation of conversion rates and the establishment of an energy balance through the determination of injected power densities.
This work will contribute to a better understanding of the mechanisms governing the process under different discharge conditions. The development of a prototype integrating the micro-plasma devices will enable deployment toward additional diagnostic methods and on-site applications, particularly for gas treatment or the local production of short-lived reactive species.

Application submission exclusively on ADUM → https://adum.fr/as/ed/voirproposition.pl?site=adumR&matricule_prop=70659