Accelerator Division

Laser irradiated foam targets: Absorption and Radiative Properties

by Mrs Martina Salvadori (Pisa University)

Europe/Rome
Aula Divisione Acceleratori (LNF INFN)

Aula Divisione Acceleratori

LNF INFN

Description
The design of specific fuel targets represents the crucial point of the Inertial Confinement Fusion scheme. In fact during the laser-matter interaction, due to the irradiation in homogeneities both parametric and hydrodynamic instabilities could be generated, leading to target pre-heating and compression inefficiency. In order to avoid these drawbacks it was considered of interest to coat fusion pellet with light foams, which can act as absorbers of the laser radiation, providing a more homogeneous irradiation and enhancing the efficiency of conversion of laser energy into shock wave energy [1,2]. The presentation will concern the results of 2016 experimental campaign, developed at ENEA research center in Frascati (Rome), in which we studied the behavior of a porous material (Polystyrene Foam) interacting with an high energy Nd laser pulse (duration 3 ns, 30J energy, focal spot dimension 100 µm). From streak camera images we estimated the volume involved in absorption and from the measurement of plasma expansion velocity it was possible to roughly estimate the plasma temperature. With semiconductor detectors we were able to get information about the X-ray emission. In particular we observed that porous materials present an X-ray emission higher than the respective solid material, being comparable to the amount emitted by an Aluminum target. Concerning the density profile, the interferometric images highlighted the presence of second harmonic emission, when irradiating solid material and its absence during the irradiation of porous plastic, which can be symptomatic of a plasma characterized by smoother density gradients [3]. References 1. R. De Angelis, F. Consoli, S.Gus'Kov, A. Rupasov, P. Andreoli, G. Cristofari and G. di Giorgio, Physics of Plasmas, 22, no. 7, p 072701 (2015). 2. A. Caruso, C. Strangio, S.Gus'Kov, and V. Rozanov, Laser and Particle Beams, 18, 1, p 25-35 (1999). 3. M. Salvadori, P. Andreoli, R. De Angelis, M. Cipriani, F. Consoli, G.Cristofari, G. di Giorgio, D. Giulietti, S.Gus'Kov, F. Ingenito and A. Rupasov, EPJ Web Of Conference, 167 (2018).
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