Interaction of relativistically strong electromagnetic waves with a layer of overdense plasma
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Interaction of Relativistically Strong Electromagnetic Waves with a Layer of Overdense Plasma A. V. Korzhimanova, V. I. Eremina,*, A. V. Kima, and M. R. Tushentsovb a Institute
of Applied Physics, Russian Academy of Sciences, ul. Ul’yanova 46, Nizhni Novgorod, 603950 Russia *e-mail: [email protected] b University of Texas at Austin, Austin, Texas, 78712 USA Received December 28, 2006
Abstract—Plasma–field structures that arise under the interaction between a relativistically strong electromagnetic wave and a layer of overdense plasma are considered within a quasistationary approximation. It is shown that, together with known solutions, which are nonlinear generalizations of skin-layer solutions, multilayer structures containing cavitation regions with completely removed electrons (ion layers) can be excited when the amplitude of the incident field exceeds a certain threshold value. Under symmetric irradiation, these cavitation regions, which play the role of self-consistent resonators, may amplify the field and accumulate electromagnetic energy. PACS numbers: 52.35.Mw, 52.38.-r, 52.50.Jm DOI: 10.1134/S1063776107100019
1. INTRODUCTION In recent years, considerable attention has been given to the problem of interaction between superstrong laser fields and a plasma. First of all, this interest has been stimulated by the impressive development of laser technologies, which allow one to produce optical pulses of intensities up to 1021 W/cm2 under experimental conditions [1]. Under such superhigh intensities, one should take into account that the oscillation energy of electrons in the field of radiation becomes comparable with their rest energy; therefore, one must take into account relativistic phenomena (see, for example, [2, 3] and the references cited therein). Similar investigations are of fundamental interest; however, they may also be useful in many practical applications, for example, in the problem of inertial nuclear fusion and the related problem of the so-called fast ignition [4]. Interestingly, under the conditions of strong relativistic interaction, plasma–field structures may arise in a plasma; in these structures, the incident field can be significantly amplified or converted to a quasistatic field. This is one of possible methods for producing strong fields for the experimental verification of the phenomena related to the nonlinearity of vacuum [5, 6]. It is well known that the interaction between relativistically strong electromagnetic radiation and a plasma is accompanied by a number of nonlinear phenomena, which include, first, the self-focusing [7] and self-channeling of a laser beam in a transparent plasma, i.e., the formation of a channel along which energy can be transmitted to large distances with small losses [8], and, second, self-induced transparency, when the optical properties of an initially nontransparent (overdense)
plasma can be substantially changed, so that it may become completely transparent [9, 10]. As is shown in a number of papers [11–14], quite extraor
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