It is known that a plasma in a magnetic field, conceived microscopically as a system of point charges, can exist in a magnetized state, and thus remain confined, inasmuch as it is in an ordered state of motion, with the charged particles performing gyrational motions transverse to the field. Here, we give an estimate of a threshold, beyond which transverse motions become chaotic, the electrons being unable to perform even one gyration, so that a breakdown should occur, with complete loss of confinement. The estimate is obtained by the methods of perturbation theory, taking as perturbing force acting on each electron that due to the so-called microfield, i.e., the electric field produced by all the other charges. We first obtain a general relation for the threshold, which involves the fluctuations of the microfield. Then, taking for such fluctuations, the formula given by Iglesias, Lebowitz, and MacGowan for the model of a one component plasma with neutralizing background, we obtain a definite formula for the threshold, which corresponds to a density limit increasing as the square of the imposed magnetic field. Such a theoretical density limit is found to fit pretty well the empirical data for collapses of fusion machines. © 2012 American Institute of Physics.

Carati, A., Zuin, M., Maiocchi, A., Marino, M., Martines, E., Galgani, L. (2012). Transition from order to chaos, and density limit, in magnetized plasmas. CHAOS, 22(3) [10.1063/1.4745851].

Transition from order to chaos, and density limit, in magnetized plasmas

Maiocchi, A;MARINO, MASSIMO;Martines, E;
2012

Abstract

It is known that a plasma in a magnetic field, conceived microscopically as a system of point charges, can exist in a magnetized state, and thus remain confined, inasmuch as it is in an ordered state of motion, with the charged particles performing gyrational motions transverse to the field. Here, we give an estimate of a threshold, beyond which transverse motions become chaotic, the electrons being unable to perform even one gyration, so that a breakdown should occur, with complete loss of confinement. The estimate is obtained by the methods of perturbation theory, taking as perturbing force acting on each electron that due to the so-called microfield, i.e., the electric field produced by all the other charges. We first obtain a general relation for the threshold, which involves the fluctuations of the microfield. Then, taking for such fluctuations, the formula given by Iglesias, Lebowitz, and MacGowan for the model of a one component plasma with neutralizing background, we obtain a definite formula for the threshold, which corresponds to a density limit increasing as the square of the imposed magnetic field. Such a theoretical density limit is found to fit pretty well the empirical data for collapses of fusion machines. © 2012 American Institute of Physics.
Articolo in rivista - Articolo scientifico
Applied Mathematics; Physics and Astronomy (all); Statistical and Nonlinear Physics; Mathematical Physics
English
2012
22
3
033124
open
Carati, A., Zuin, M., Maiocchi, A., Marino, M., Martines, E., Galgani, L. (2012). Transition from order to chaos, and density limit, in magnetized plasmas. CHAOS, 22(3) [10.1063/1.4745851].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/78181
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