Role of the Hall flute instability in the interaction of laser and space plasmas with a magnetic field
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MA INSTABILITY
Role of the Hall Flute Instability in the Interaction of Laser and Space Plasmas with a Magnetic Field Yu. P. Zakharova, V. M. Antonova, E. L. Boyarintseva, A. V. Melekhova, V. G. Posukha, I. F. Shaikhislamova, and V. V. Pickalovb a Institute
of Laser Physics, Siberian Division, Russian Academy of Sciences, pr. Akademika Lavrent’eva 13/3, Novosibirsk, 630090 Russia b Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, Institutskaya ul. 4/1, Novosibirsk, 630090 Russia Received December 12, 2004; in final form, March 30, 2005
Abstract—The interaction of an expanding laser plasma with a uniform external magnetic field is studied over a wide range of experimental parameters (for a plasma energy of up to 300 J and a magnetic induction of up to 8 kG). By analyzing the data from these and other experiments, as well as the results of simulations with the use of a two-fluid Hall plasma model, it was found for the first time that the flute instability of the plasma boundary plays a decisive role in the process of the plasma cloud expansion. It is shown that, when the ion Larmor radius is sufficiently large, this instability can significantly affect the maximum radius of the diamagnetic cavity of the plasma cloud and the deceleration of its front by the magnetic field. A physical model based on the Hall effect is proposed to explain such influence. The model adequately describes data from one-dimensional simulations, as well as from experiments with quasi-spherical laser plasma clouds. The results obtained can be helpful in interpreting the data from active magnetospheric experiments with barium plasma clouds (such as AMPTE) and analyzing the plasma dynamics in future ICF reactors and propulsion systems with a magnetic field for direct conversion of fusion energy into electric energy. PACS numbers: 52.35.–g, 52.35.Mw, 52.35.Py DOI: 10.1134/S1063780X06030020
1. INTRODUCTION Over the past few decades, a great deal of experimental effort has been devoted to studies of the expansion of laser-produced plasma into a vacuum in a uniform external magnetic field B0 (see, e.g. [1–19]). Besides solving a wide range of fundamental problems (such as plasma diamagnetism; plasma instabilities; and the deceleration, trapping, and heating of plasma in a magnetic field), many of these studies [8–12, 15–17, 19] were aimed at laboratory simulations [20–22] of the plasma expansion in space, in particular, in AMPTE [23] and CRRES [24] experiments on barium release into the Earth’s magnetosphere. A common phenomenon revealed in these studies was an abnormally fast development of a specific (non-MHD) type of flute instability of the plasma boundary with a characteristic wavelength λ ≤ RL, where RL is the ion Larmor radius, which, as applied to this problem, is defined as RL = mcV0 /zeB0, with V0 being the expansion velocity of the plasma cloud. This type of Rayleigh–Taylor flute instability, which is also known as the large Larmor radius (LLR) instability [9, 12], is still poorly investiga
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