Short-wavelength experiments on laser pulse interaction with extended pre-plasma at the PALS-installation

Year: 2016

Authors: Pisarczyc T., Guskov SYu., Renner O., Dudzak R., Dostal J., Demchenkmo LL., Smid M., Chodukowsi T., Kalinowska Z., Rosinski M., Parys P., Badziak J., Batani D., Borodziuk S., Gizzi LA., Krousky E., Maheut Y., Cristoforetti G., Antonelli L., Koester P., Baffigi F., Ullshmied J., Hrebicek J., Medrik T., Pfeifer M., Skala J., Pisarczyc P.

Autors Affiliation: Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland; P.N. Lebedev Physical Institute of RAS, Moscow, Russian Federation; National Research Nuclear University (Moscow Eng. Phys. Inst.), Moscow, Russian Federation; Institute of Physics ASCR, Prague, Czech Republic; Institute of Plasma Physics ASCR, Prague, Czech Republic; Université Bordeaux, CNRS, CEA, CELIA, Talence, France; Intense Laser Irradiation Laboratory-National Institute of Optics CNR, Pisa, Italy; Warsaw University of Technology, Institute of Computer Sciences, Warsaw, Poland

Abstract: The paper is a continuation of research carried out at Prague Asterix Laser System (PALS) related to the shock ignition (SI) approach in inertial fusion, which was carried out with use of 1 omega main laser beam as the main beam generating a shock wave. Two-layer targets were used, consisting of Cu massive planar target coated with a thin polyethylene layer, which, in the case of two-beam irradiation geometry, simulate conditions related to the SI scenario. The investigations presented in this paper are related to the use of 3 omega to create ablation pressure for high-power shock wave generation. The interferometric studies of the ablative plasma expansion, complemented by measurements of crater volumes and K-alpha emission, clearly demonstrate the effect of changing the incident laser intensity due to changing the focal radius on efficiency of laser energy transfer to a shock wave and fast electron emission. The efficiency of the energy transfer increases with the radius of the focused laser beam. The pre-plasma does not significantly change the character of this effect. However, it unambiguously results in the increasing temperature of fast electrons, the total energy of which remains very small (<0.1% of the laser energy). This study shows that the optimal radius from the point of view of 3 omega radiation energy transfer to the shock wave is the maximal one used in these experiments and equal to 200 mu m that corresponds to the minimal effect of two-dimensional (2D)-expansion. Such a result is typical for the ablation process determined by electron conductivity energy transfer under the conditions of one-dimensional or 2D matter expansion without any appreciable effect due to energy transfer by fast electrons. The 2D simulations based on application of the ALANT-HE code and an analytical model that includes generation and transport of hot electrons has been used to support of experimental data. Journal/Review: LASER AND PARTICLE BEAMS

Volume: 34 (1)      Pages from: 94  to: 108

More Information: This paper was supported in part by the Access to Research Infrastructure activity in the 7th Framework Program of the EU Contract No. 284464, Laserlab Europe III, by the Czech Republic
KeyWords: Laser-produced plasma; Shock ignition; Fast electrons; Energy transport; Femtosecond interferometry
DOI: 10.1017/S0263034615000993

Citations: 7
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