JCJC - Jeunes chercheuses & jeunes chercheurs

Dynamique de l'instabilité de MIcro-gouttelettes Chargées – DynaMIC

Submission summary

When increasing the electric charge of a finite-size system, at a certain point it becomes unstable. The Coulomb instability has been studied in the case of fissile nuclei, metal clusters and micro-droplets. However, the study of the deformation dynamics leading to fission remains a difficult task. From preliminary calculations, we deduce that the charge mobility and the viscosity are crucial characteristics, which influence the fission dynamics of micro-droplets. We propose here to study, for the complete shape deformation of a charged micro-droplet and to put into evidence the influence of the droplet properties like charge mobility, viscosity, surface tension, initial charge state and external electric field on the deformation dynamics. We will address the problem from both experimental and theoretical side. We propose to develop a numerical model based on the Navier-Stokes equation, in which the fluid properties appear explicitly. This original work will allow, for the first time, to simulate the full fission dynamics and to quantify the Coulomb Instability and subsequent fission dynamics in terms of deformation energy, deformation geometry, characteristic time and physical observable of the final shape of the droplet just before fission. In the same time, we will produce new experimental results by monitoring the deformation dynamics of metallic droplets in order to valid the model, as presently only a few observations of the deformation dynamics of critically charged micro-droplets exist. We want to trap micro-droplets (mercury or galinstan) under ambient pressure and measure the influence of the viscosity (the only free parameter, as the conductivity is infinite) on the deformation dynamics and subsequent fission. Furthermore, we propose to realize innovative experiments of Coulomb instabilities for droplets charged above the Rayleigh limit. The trapped microdroplets will be put under vacuum and prepared in a supercritical state (X> 1) by collision with highly charged ions. We will be able to test and verify the predictions of the hydrodynamic model. Once the model has been validated using the expected results that will be measured by the team, one will be able to understand under what conditions the systems breaks up and what are the dominant feature of the different fragmentation channels.

Project coordination

Eric GIGLIO (Organisme de recherche)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

Help of the ANR 135,000 euros
Beginning and duration of the scientific project: - 36 Months

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