UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2015 Meeting


Section: Optics, Spectroscopy, Plasma and Lasers


Title:
PIC modeling of ultrashort and intense laser pulse interaction with overdense plasmas


Authors:
Andreea MIHAILESCU, Viorica STANCALIE


Affiliation:
National Institute for Laser, Plasma &Radiation Physics, Department of Lasers,

Atomistilor 409, P.O.Box MG-36, Magurele-Ilfov, 077125 ROMANIA



E-mail
andreea.floryn@gmail.com, andreea.mihailescu@inflpr.ro


Keywords:
laser-plasma interaction, overdense plasmas, ultrashort and intense laser pulses, particle-in-cell, high harmonics generation


Abstract:
High order harmonics generated at the interaction of ultrashort and intense laser pulses with plasma are a promising diagnostics tool for gaining insight on plasma parameters such as local electron density, plasma expansion velocity as well as on strong electric and magnetic fields or electron transport within the target. Using an overdense plasma layer is of particular interest as there is no limitation in terms of incident laser intensity, a higher laser intensity strongly enhancing the production of harmonics. This is an important consequence, allowing applications ranging from non-linear optics in XUV region to opacity measurements of warm and hot high-density matter with high temporal and spatial resolution. In this paper, we simulate the interaction of an ultrashort and intense laser pulse, with the laser intensity ranging from in the femtosecond regime- both at normal and oblique incidence- with overdense aluminium plasma layers. Harmonics generated with fs laser pulses are among the most intense sources in the wavelength range of a few tens of nanometers, being a coherent source much brighter than the other XUV sources, apart from the XFEL. Making use of the 1D3V particle in cell LPIC++ code, we analyze the spectra obtained when the laser intensity, its polarization and the initial electron density within the plasma layer are varied. Detailed measurement of the polarization dependence of high harmonics generated using femtosecond laser pulses have not yet been reported. It is therefore, the purpose of this study to offer an insight on the influence of the polarization of an incident fs laser pulse on the high harmonics generation mechanism. Furthermore, insights on how the direct laser-plasma heating mechanisms emerge and evolve according to the different interaction scenarios are provided and discussed.


Acknowledgement:
This work is supported by the Institute of Atomic Physics under project no. F03 - SCAFI. Financial support under the Romanian Space Agency coordinated program STAR Project Number 33 is also acknowledged.