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9Complex Systems of Charged Particles and their Interactions with Electromagnetic Radiation 2016
X-RAY SPECTROSCOPY DIAGNOSTICS ON SUPERSONIC ASTROPHYSICALLY-
RELEVANT PLASMA JETS
S.A. Pikuz1,2, E.D. Filippov1,2, S.N. Ryazantsev1,3, I.Yu. Skobelev1,2, G. Revet4,5, D P. Higginson4,6, S.N. Chen4, B. Albertazzi4,7, A.A. Soloviev5, J. Beard8, B. Khiar9, A.
Ciardi9, A.Ya. Faenov1,10, H. Pepin11, and J. Fuchs4,5
1 Joint Institute for High Temperatures RAS, Moscow 125412, Russia 2 National Research Nuclear University 'MEPhI', Moscow115409, Russia 3 Lomonosov Moscow State University, Moscow 119991, Russia 4 Laboratoire pour I'Utilisation des Lasers Intenses, CNRS-CEA-Ecole Polytechnique, Palaiseau
91128, France
5 Institute of Applied Physics RAS, Nizhny Novgorod 603950, Russia 6 Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
7 Graduate School of Engineering Osaka University, Suita, Osaka 565-087, Japan 8 LNCMI, UPR 3228, CNRS-UJF-UPS-INSA, 31400 Toulouse, France 9 LERMA, Observatoire de Paris, PSL Research University, CNRS, Paris 75014, France 10 Institute for Academic Initiatives, Osaka University, Suita, Osaka 565-0871, Japan 11 Centre Energie Materiaux Telecommunications INRS, Varennes J3X1S2, Quebec, Canada
spikuz@gmail.com
Remarkable plasma hydrodynamic phenomena such as supersonic jets have been observed to emerge from a wide variety of astrophysical systems, however the questions on their formation mechanisms and morphology are still open. Laboratory experiments employing the plasma produced by high power lasers can be scaled to astrophysical systems by matching dimensionless scaling parameters and thus providing the studies of astrophysical phenomena in controllable conditions. Particularly, laser produced jets are fully scalable to that one from young star objects, and the application of external magnetic field to plasma flows allows to investigate stable, large aspect ratio plasma jets.
While the laser produced plasma expands from the target surface, it becomes overcooled, i.e. recombining one, and with non-stationary ionization state in the most of cases. Accordingly, to improve diagnostic methods applicable for such plasma is rather important task in laboratory astrophysics.
In present work, X-ray spectroscopy method considering the relative intensities of spectral lines emitted by He-like and H-like F and O ions is developed and implemented to determine electron temperature Te and density Ne profiles of plasma jets along its propagation in vacuum, external magnetic field and ambient gas. It is shown that Ne decreases monotonically in the case without B-field, but demonstrates an extended density profile when 20 T poloidal magnetic field is applied. While at target surface irradiated by 60 J 1 ns laser pulses the electron temperature peaks at 250-280 eV, at 3 mm distance it cools down to ~ 20 eV. Then, due to the impact of B field providing the collimation of the jet, Te and Ne are measured to keep at almost constant values for a long distance along the jet. Laboratory experiments reveal that the shaping of narrow jets emerging from young stars can be explained by axial magnetic fields in which the stars are embedded.
