Study of mechanisms for magnetic field diffusion into an expanding laser plasma
- PDF / 430,402 Bytes
- 14 Pages / 612 x 792 pts (letter) Page_size
- 99 Downloads / 146 Views
A DYNAMICS
Study of Mechanisms for Magnetic Field Diffusion into an Expanding Laser Plasma A. V. Bessarab, G. A. Bondarenko, G. V. Dolgoleva, V. A. Zhmaœlo, A. V. Kunin, I. N. Nikitin, E. A. Novikova, V. P. Statsenko, and R. R. Sungatullin All-Russia Research Institute of Experimental Physics, Russian Federal Nuclear Center, pr. Mira 37, Sarov, Nizhni Novgorod oblast, 607190 Russia Received April 20, 2006; in final form, December 22, 2006
Abstract—The interaction of plasma clouds generated during laser irradiation of a spherical target in a background gas with a magnetic field was studied on the MKV-4 test bench of the Iskra-5 facility. The dynamics of the plasma cloud expansion in a 300- to 500-Oe magnetic field was investigated using magnetic and probe diagnostics. The results obtained are compared with calculations by different models of laser plasma diffusion in a magnetic field. PACS numbers: 52.50.Jm, 52.50.Kz, 52.72.+v DOI: 10.1134/S1063780X07100030
INTRODUCTION Studies of the interaction of plasma clouds with an external magnetic field are of interest for a variety of applied and fundamental problems, such as plasma magnetic confinement, the dynamics of plasma clouds in the Earth’s magnetosphere, and the interaction of supernova remnants with the interstellar magnetic field. These phenomena have recently begun to be simulated by using laser facilities (see, e.g., [1–9] and references therein); in particular, the effects of plasma deceleration by a magnetic field and the field perturbations caused by plasma expansion have been investigated. It is found that the interpenetration of an expanding plasma and a magnetic field is more efficient than it could be expected in the case of classical collisional diffusion. This effect was first observed in [4, 10], where it was attributed to the development of kinetic instabilities [11] in an expanding plasma. In more recent papers (see, [7, 9]), it was examined with allowance for available experimental data by analogy with the Rayleigh– Taylor instability. In the present paper, a semiempirical model that incorporates both of the above two approaches is formulated on the basis of the previous results. To verify the basic assumptions of this model, a series of experiments were carried out on the MKV-4 test bench of the Iskra-5 facility [12]. The experimental design was close to that of the experiments performed previously on the KI-1 test bench [2–5], the main differences being the shorter wavelength and higher power of laser radiation, as well as the use of another type of target.
In Section 1, the design of the experiment is described, and, in Section 2, the measurement data are compared with the results of computer simulations. 1. EXPERIMENTAL SETUP AND MEASUREMENT RESULTS The experiments on studying the expansion of plasma clouds in an external magnetic field were carried out on the MKV-4 test bench installed in one of the channels of the Iskra-5 iodine laser facility [13]. The test bench was a 1.5-m-long 1-m-diameter cylindrical vacuum chamber equipped with a pump
Data Loading...
