Cylindrical and spherical ion-acoustic envelope solitons in multicomponent plasmas with positrons

R. Sabry, W. M. Moslem, P. K. Shukla, and H. Saleem

Phys. Rev. E 79, 056402 – Published 6 May 2009

Abstract

The nonlinear wave modulation of planar and nonplanar (cylindrical and spherical) ion-acoustic envelope solitons in a collisionless unmagnetized electron-positron-ion plasma with two-electron temperature distributions has been studied. The reductive perturbative technique is used to obtain a modified nonlinear Schrödinger equation, which includes a damping term that accounts for the geometrical effect. The critical wave number threshold $K_{c}$ , which indicates where the modulational instability sets in, has been determined for various regimes. It is found that an increase in the positron concentration $(α)$ leads to a decrease in the critical wave number $(K_{c})$ until $α$ approaches certain value $α_{c}$ (critical positron concentration), then further increase in $α$ beyond $α_{c}$ increases the value of $K_{c}$ . Also, it is found that there is a modulation instability period for the cylindrical and spherical wave modulation, which does not exist in the one-dimensional case.

Received 16 January 2009

DOI:https://doi.org/10.1103/PhysRevE.79.056402

Authors & Affiliations

R. Sabry^1,*, W. M. Moslem^2,†, P. K. Shukla^1,3,‡, and H. Saleem³

¹Institut für Theoretische Physik IV, Fakultät für Physik und Astronomie, Ruhr-Universität Bochum, D-44780 Bochum, Germany
²Department of Physics, Faculty of Science-Port Said, Suez Canal University, Port Said, Egypt
³National Center for Physics, Quaid-i-Azam University Campus, Islamabad, Pakistan

^*Also at Theoretical Physics Group, Department of Physics, Faculty of Science, Mansoura University, Damietta Branch, New Damietta 34517, Egypt; sabryphys@yahoo.com and sabry@tp4.rub.de
^†wmmoslem@hotmail.com and wmm@tp4.rub.de
^‡Also at the Nonlinear Physics Centre and Center for Plasma Science and Astrophysics, Ruhr-Universität Bochum, D-44780 Bochum, Germany; Department of Physics, Umeå University, SE-90187 Umeå, Sweden; Max-Planck-Institut für extraterrestrische Physik, D-85741 Garching, Germany; GoLP/Institute of Plasmas and Nuclear Fusion, Instituto Superior Técnico, 1049-001 Lisbon, Portugal; CCLRC Centre for Fundamental Physics, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon 0X11 0QX, UK; SUPA Department of Physics, University of Strathclyde, Glasgow G 40NG, UK; School of Physics, Faculty of Science and Agriculture, University of Kwazulu-Natal, Durban 4000, South Africa; ps@tp4.rub.de

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Issue

Vol. 79, Iss. 5 — May 2009

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