Astrophys Space Sci (2007) 307:87–91 DOI 10.1007/s10509-006-9222-9 ORIGINAL ARTICLE How Produce a Plasma Jet Using a Single and Low Energy Laser Beam Ph. Nicola¨ ı · V. T. Tikhonchuk · A. Kasperczuk · T. Pisarczyk · S. Borodziuk · K. Rohlena · J. Ullschmied Received: 10 April 2006 / Accepted: 18 July 2006 C  Springer Science + Business Media B.V. 2006 Abstract Under suitable conditions on laser intensity, focal spot radius and atomic number a radiative jet was launched from a planar target. This jet was produced using a relatively low energy laser pulse, below 500 J and it presents similar- ities with astrophysical protostellar jets. It lasts more than 10 ns, extends over several millimeters, has velocity more than 500 km/s, the Mach number more than 10 and the den- sity above 10 18 cm −3 . The mechanism of jet formation was inferred from the dimensional analysis and hydrodynamic two-dimensional simulations. It is related to the radiative cooling while the magnetic fields play a minor role. Keywords Jets . Outflows . Laser-plasma PACS numbers: 98.38.Fs, 52.50.Jm, 95.30.Qd 1. Introduction The jets are ubiquitous in the Universe, from active galactic nuclei (Cecil et al., 1992; Bride and Perley, 1984) to Young P. Nicola¨ ı() · V. T. Tikhonchuk Centre Lasers Intenses et Applications, UMR 5107 CEA – CNRS – Universit´ e Bordeaux 1, 33405 Talence cedex, France e-mail: nicolai@celia.u-bordeaux1.fr A. Kasperczuk · T. Pisarczyk · S. Borodziuk Institute of Plasma Physics and Laser Microfusion, ul. Hery 23, 00-908 Warsaw 49, Poland K. Rohlena Institute of Physics AS CR, Na Slovance 2, 182 21 Prague 8, Czech Republic J. Ullschmied Institute of Plasma Physics AS CR, Za Slovankou 3, 182 00 Prague 8, Czech Republic Stellar Objects (Zinnecker et al., 1998; Reipurth et al., 1986) (YSO). The physics involved in jets formation is compli- cated and covers a large range of subjects. Consequently the numerical simulations require multidimensional codes accounting for hydrodynamics, ionization, radiation trans- port, equations of state and magnetic fields. The complexity of the phenomenon makes it challenging to devise labora- tory experiments which are needed to benchmark the codes and to model certain aspects of large scale astrophysical phenomena. Recent experiments, carried out with Z-pinches (Lebedev et al., 2002; Ampleford et al., 2005) or with high energy lasers (Farley et al., 1999; Shigemori et al., 2000; Foster et al., 2002; Rosen et al., 2005) showed the interest and the relevance of the laboratory jets to some astrophysical jets. In these experiments, jets were produced from a radia- tive collapse of a convergent plasma flow or a shock wave, at a stagnation point. In terms of the experiment geometry, this method of jet production requires a high energy and/or a multiple laser beams. The present study addresses the problem of jet formation using a single and low energy laser beam. The experiments were carried out at the Prague Asterix Laser System (PALS) iodine laser facility (Jungwirth et al., 2001). The experimental images showed a jet formation under certain conditions (Borodziuk et al., 2004; Kasperczuk et al., 2006). Although the radiative effects are important, the jet creation is neither induced by plasma collision nor by shock convergence. The numerical simulations carried out with a multi-physics, two-dimensional (2D) radiative magneto-hydrodynamic code (Buresi et al., 1986; Drevet, 1997; Nicola ¨ i et al., 2000). It was found out that the main mechanism which transforms the ablated plasma in a plasma jet is the radiative cooling of expanding plasma. Under appropriate conditions on the laser energy and the focal spot radius, the jet is formed having a Mach number larger than Springer