AHUIR, Jérémy (2016) Study of the explosion of the plasma channel created by an ultra-intense laser in a gas of helium PRE - Research Project, ENSTA.

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Abstract

The interaction between a femtosecond laser and a jet of sub-dense helium leads to the creation of a wakefield within the engendered plasma. This interaction induces the emergence of an annular structure, compound of an essentially ionic channel and an essentially electronic shell, undergoing a priori a coulombian explosion. The image processing by wavelet analysis and Abel inversion based on a series of shootings realized on a jet of quasi-gaussian gas in Salle Jaune supplies the evolution of the characteristic size of the channel according to the time and the density of the jet. The channel undergoes then a transition phase, strongly dependent on the density, and a ‘’shock’’ phase, which has a stable behavior. Two regimes appear within the transition phase : a "high densities" regime, where the channel seems to contract, and a "low densities" regime, which seems to correspond to a classic explosion. The study of the shocks shows a change of the behavior of the shock wave according to the density of the jet. This phenomenon is potentially explainable by a gradient of density. The study of trajectories shows that the coulombian explosion itself is not enough to report the explosion of the channel.

Item Type:Thesis (PRE - Research Project)
Uncontrolled Keywords:femtosecond laser, plasma, channel, coulombian explosion, shockwaves
Subjects:Physics, Optics
ID Code:6708
Deposited By:Jérémy Ahuir
Deposited On:07 sept. 2016 16:52
Dernière modification:07 sept. 2016 16:52

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