Article

# Interaction of a weakly nonlinear laser pulse with a plasma.

University of Southern California;

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics 03/1993; 47(2):1249-1261. DOI: 10.1103/PhysRevE.47.1249 Source: PubMed

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**ABSTRACT:**An analytical and numerical investigation is presented of the behavior of a linearly polarized electromagnetic pulse as it propagates through a plasma. Considering a weakly relativistic regime, the system of one-dimensional fluid-Maxwell equations is reduced to a generalized nonlinear Schrödinger type equation, which is solved numerically using a split step Fourier method. The spatio-temporal evolution of an electromagnetic pulse is investigated. The evolution of the envelope amplitude of density harmonics is also studied. An electromagnetic pulse propagating through the plasma tends to broaden due to dispersion, while the nonlinear frequency shift is observed to slow down the pulse at a speed lower than the group velocity. Such nonlinear effects are more important for higher density plasmas. The pulse broadening factor is calculated numerically, and is shown to be related to the background plasma density. In particular, the broadening effect appears to be stronger for dense plasmas. The relation to existing results on electromagnetic pulses in laser plasmas is discussed.Physics of Plasmas 01/2008; 15. · 2.38 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**The reductive perturbation method is used to derive a generic form of nonlinear Schroedinger equation (NLSE) that describes the nonlinear evolution of electrostatic (ES)/electromagnetic (EM) waves in fully relativistic two-fluid plasmas. The matrix eigenvector analysis shows that there are two mutually exclusive modes of waves, each mode involving only either one of two electric potentials, A and {phi}. The general result is applied to the electromagnetic mode in electron-ion plasmas with relativistically high electron temperature (T{sub e} Much-Greater-Than m{sub e}c{sup 2}). In the limit of high frequency (ck Much-Greater-Than {omega}{sub e}), the NLSE predicts bump type electromagnetic soliton structures having width scaling as {approx}kT{sub e}{sup 5/2}. It is shown that, in electron-positron pair plasmas with high temperature, dip type electromagnetic solitons can exist. The NLSE is also applied to electrostatic (Langmuir) wave and it is shown that dip type solitons can exist if k{lambda}{sub D} Much-Less-Than 1, where {lambda}{sub D} is the electron's Debye length. For the k{lambda}{sub D} Much-Greater-Than 1, however, the solution is of bump type soliton with width scaling as {approx}1/(k{sup 5}T{sub e}). It is also shown that dip type solitons can exist in cold plasmas having relativistically high streaming speed.Physics of Plasmas 08/2012; 19(8). · 2.38 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**A strong correlation is observed between the formation of electromagnetic solitons, generated during the interaction of a short intense laser pulse (30 fs, ∼1018 W/cm2) with a rarefied (<0.1nc) plasma, and pulse self-focusing. Pulse defocusing, which occurs after soliton generation, results in laser-pulse energy depletion. The role of stimulated Raman scattering in soliton generation is analyzed from 2D particle-in-cell simulations. An observed relationship between initial plasma density and soliton generation is presented that might have relevance to wake-field accelerators.Physics of Plasmas 10/2012; 19(10). · 2.38 Impact Factor

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