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Nonlinear evolution of Langmuir and electromagnetic pulses in a warm, unmagnetized plasma: modulational instability, integrability and self-focusing in 2 + 1 dimensions

Published online by Cambridge University Press:  13 March 2009

Ronald E. Kates
Affiliation:
Astrophysical Institute Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
D. J. Kaup
Affiliation:
Clarkson University, Potsdam, New York 13676, U.S.A.

Abstract

The nonlinear dynamics of wave envelopes modulated in 2 + 1 dimensions is considered for two systems in plasma physics: (i) Langmuir pulses and (ii) intense (but weakly relativistic) electromagnetic (EM) pulses. Using singular perturbation techniques applied to an envelope approximation, both problems are reduced to the two-dimensional nonlinear Schrödinger (2DNLS) system, which describes the dynamics of two coupled slowly varying potentials. The general 2DNLS system exhibits a rich variety of phenomena, including enhanced (compared with ‘longitudinal’ propagation) modulational stability and (1D) soliton formation; decay of 1D solitons over long time scales; self- focusing regimes (determined by a virial-type condition); as well as integrability and 2D solitons. Applying our recent results on the 2DNLS system, we determine which of these phenomena can actually occur here and compute the parameter regimes. (i) The 2DNLS system for the Zakharov equations is modulationally unstable for all parameter values. It also has an integrable sector and a self-focusing regime. (ii) The 2DNLS system describes coupled ‘longitudinal’ and ‘transverse’ modulations of linearly or circularly polarized EM pulses propagating through a warm unmagnetized two-component neutral plasma with arbitrary masses (i.e. electron—positron or electron—ion). The pulse can accelerate particles to weakly (but not fully) relativistic velocities; relativistic, ponderomotive and harmonic effects all contribute to the nonlinear terms. The resulting 2DNLS system does not admit a self-focusing regime. Parameter values leading to an integrable case (the so-called ‘Davey—Stewartson I’ equations, which admit 2D soliton solutions) are computed; however, the required values would not be attainable in a laboratory or astrophysical setting. None the less, the existence of new nonlinear modulational instabilities associated with the second spatial degree of freedom already represents an important potential limitation on any (1 + 1)-dimensional approach to nonlinear evolution and modulational instability of plasma EM waves.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1994

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References

Ablowitz, M. & Segur, H. 1979 J. Fluid Mech. 92, 691.CrossRefGoogle Scholar
Berezhiani, V. I., Tsintsadze, N. L. & Tskhakaya, D. D. 1980 J. Plasma Phys. 24, 15.CrossRefGoogle Scholar
Borisov, A., Borosvskiy, A. V., Kotobkin, V. V., Prokhorov, A. M., Rhodes, C. K. & Shiryaev, O. B. 1992 a Phys. Rev. Lett. 65, 1753.CrossRefGoogle Scholar
Borisov, A., Borovskiy, A. V., Shiryaev, O. B., Krobkin, V. V., Prokhorov, A. M., Solem, J. C., Luk, T. S., Boyer, K. & Rhodes, C. K., 1992 b Phys. Rev. A 45, 5830.CrossRefGoogle Scholar
Djordjevic, V. & Redekopp, L. 1977 J. Fluid Mech. 79, 703.CrossRefGoogle Scholar
Goldman, M. 1984 Rev. Mod. Phys. 56, 709.CrossRefGoogle Scholar
Karpman, V. 1990 “Nonlinear Interaction between Short and Long Waves”, pp. 83160, article in Conte, R. & Boccara, N., Partially Integrable Evolution Equations in Physics [Kluwer Academic Publishers, Boston (1990)].CrossRefGoogle Scholar
Karpman, V. & Washimi, H. 1977 J. Plasma Phys. 18, 173.CrossRefGoogle Scholar
Kates, R. & Kaup, D. 1989 a J. Plasma Phys. 42, 507 (Paper I).CrossRefGoogle Scholar
Kates, R. & Kaup, B. 1989 b J. Plasma Phys. 42, 521 (Paper II).CrossRefGoogle Scholar
Kstes, R. & Kaup, B. 1991 J. Plasma Phys. 46, 85 (Paper III).Google Scholar
Kates, R. & Kaup, B. 1992 J. Plasma Phys. 48, 119 (Paper IV).CrossRefGoogle Scholar
Kates, R. & Kaup, B. 1993 J. Plasma Phys. 48, 397 (Paper V).CrossRefGoogle Scholar
Kates, R. & Kaup, B. 1994 Two-dimensional nonlinear Schrödinger equations and their properties. Physica D (to appear), (Paper 0).CrossRefGoogle Scholar
Rizzato, F. B. & Chian, A. C.-L. 1992 J. Plasma Phys. 48, 71.CrossRefGoogle Scholar
Shukla, P. & Stenflo, L. 1984 Phys. Rev. A 30, 2110.CrossRefGoogle Scholar
Spatschek, K. 1977 J. Plasma Phys. 18, 293.CrossRefGoogle Scholar
Zakharov, V. E. 1972 Soviet Phys. JETP 35, 908Google Scholar
[Zh. Eksp. Teor. Piz. 62, 1745 (1972)].Google Scholar
Zakharov, V. E. & Rubenchik, A. M. 1972 Prikl. Mekh. Tekh. Fiz. No. 5, 84Google Scholar
[J. Appl. Math. Tech. Phys. 13, 669 (1974)].CrossRefGoogle Scholar