Study of the glow dynamics in a laser-produced plasma jet expanding across the magnetic field
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Study of the Glow Dynamics in a LaserProduced Plasma Jet Expanding Across the Magnetic Field A. V. Bessarab, G. A. Bondarenko, S. G. Garanin, N. V. Zhidkov, I. N. Nikitin, V. A. Starodubtsev, and R. R. Sungatullin Russian Federal Nuclear Center, AllRussia Research Institute of Experimental Physics, Sarov, Nizhni Novgorod oblast, 607188 Russia Received February 18, 2010; in final form, February 4, 2011
Abstract—Results are presented from experimental studies of the glow dynamics of a plasma jet generated during the irradiation of a plane aluminum target by an iodine laser pulse with the wavelength 1.315 μm. The laser pulse energy was 330–480 J, the pulse duration was 0.5 ns, and the focal spot diameter was 3 mm, the laser intensity on the target surface being ~1013 W/cm2. The jet expanded across an external magnetic field with the strength ~1 kOe. The residual air pressure in the vacuum chamber was ~10–5 Torr. The spatiotem poral behavior of the jet glow was investigated using a nineframe camera in two mutually perpendicular directions (along and across the magnetic field). The results of measurements indicate azimuthal asymmetry of the jet expansion. DOI: 10.1134/S1063780X1107004X
1. INTRODUCTION Various processes occurring in the solar corona and the Earth’s magnetosphere are characterized by the generation of plasma jets and their interaction with the magnetic field. Similar problems also arise in astro physics and controlled fusion research. This stimu lated extensive studies on the modeling of these pro cesses in laboratory facilities. In some experiments (see, e.g., [1, 2]), the plasma jets are generated using electrodynamic generators, while in other experi ments [3–7], they are produced by irradiating a plane target with highpower laser pulses. In the present study, the latter approach was used. The experiments were carried out in a vacuum chamber placed in one of the channels of the Iskra5 laser facility [8], which allows one to generate plasma jets with particle veloc ities substantially higher than those in [1, 2] and ener gies substantially exceeding those in [3–7]. It should be noted that the present experiments continue our previous studies performed at this facility [9–12]. In [9–11], the kinetic and radiative processes occurring in a plasma cloud produced in the chamber atmo sphere during the irradiation of spherical targets with out a magnetic field were investigated, whereas in [12], similar experiments were carried out in the presence of a magnetic field. The attention was mainly paid to investigating mechanisms of field diffusion into the plasma. The parameters of the field and plasma in those experiments were such that the effect of the magnetic field on the plasma dynamics could be ignored. The main difference of the present study from the previous experiments [9–12] is the use of plane tar
gets. This allowed us to generate a plasma cloud in the form of a jet and study the glow dynamics of this jet during its expansion across the magnetic field. 2. EXPERIMENTAL LAYOUT
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