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Full-Text Articles in Numerical Analysis and Computation

Compression Of Laser Radiation In Plasmas Using Electromagnetic Cascading, Serguei Y. Kalmykov, Gennady Shvets Jun 2005

Compression Of Laser Radiation In Plasmas Using Electromagnetic Cascading, Serguei Y. Kalmykov, Gennady Shvets

Serge Youri Kalmykov

Compressing high-power laser beams in plasmas via generation of a coherent cascade of electromagnetic sidebands is described. The technique requires two copropagating beams detuned by a near-resonant frequency, \Omega < \omega_{p}. The ponderomotive force of the laser beat wave drives an electron plasma wave which modifies the refractive index of plasma so as to produce a periodic phase modulation of the laser field with the beat period t_b = 2\pi/\Omega. A train of chirped laser beat notes (each of duration t_b) is thus created. The group velocity dispersion of radiation in plasma can then compress each beat note to a few-laser-cycle duration. As a result, a train of sharp electromagnetic spikes separated in time by t_b is formed. Depending on the plasma and laser parameters, chirping and compression can be implemented either concurrently in the same plasma or sequentially in different plasmas.


Strongly Coupled Large-Angle Stimulated Raman Scattering Of Short Laser Pulse In Plasma-Filled Capillary, Serguei Y. Kalmykov, Patrick Mora Apr 2005

Strongly Coupled Large-Angle Stimulated Raman Scattering Of Short Laser Pulse In Plasma-Filled Capillary, Serguei Y. Kalmykov, Patrick Mora

Serge Youri Kalmykov

Strongly coupled large-angle stimulated Raman scattering sLA SRSd of a short intense laser pulse develops in a plane plasma-filled capillary differently than in a plasma with open boundaries. Coupling the laser pulse to a capillary seeds the LA SRS in the forward direction (scattering angle smaller than \pi / 2 ) and can thus produce a high instability level in the vicinity of the entrance plane. In addition, oblique mirror reflections off capillary walls partly suppress the lateral convection of scattered radiation and increase the growth rate of the SRS under arbitrary (not too small) angle. Hence, the saturated convective …


Laser Wakefield Acceleration By Petawatt Ultrashort Laser Pulses, Leonid M. Gorbunov, Serguei Y. Kalmykov, Patrick Mora Feb 2005

Laser Wakefield Acceleration By Petawatt Ultrashort Laser Pulses, Leonid M. Gorbunov, Serguei Y. Kalmykov, Patrick Mora

Serge Youri Kalmykov

An ultrashort (about 30 fs) petawatt laser pulse focused with a wide focal spot (about 100 mm) in a rarefied plasma (n_0 ~ 10^{17} cm^{−3}) excites a nonlinear plasma wakefield which can accelerate injected electrons up to GeV energies without any pulse channeling. Under these conditions, propagation of the laser pulse with an overcritical power for relativistic self-focusing is almost the same as in vacuum. The nonlinear quasiplane plasma wave, whose amplitude and phase velocity vary along the laser path, effectively traps and accelerates injected electrons with a wide range of initial energies. Electrons accelerated over two Rayleigh lengths (about …


A Posteriori Estimate For Tikhonov Regularization Parameter, S. Abbasbandy Jan 2005

A Posteriori Estimate For Tikhonov Regularization Parameter, S. Abbasbandy

Saeid Abbasbandy

This paper deals the numerical solution of integral equations of the first kind with using regularization method. There are many stopping rules based on discrepancy principle or discussed in [3]. Here a new stopping rule is described which uses SVD (Singular Value Decomposition) and condition number of matrices. Finally, we give a number of numerical examples showing that the method works well in practice.


A Method For Solving Fuzzy Linear Systems, S. Abbasbandy, M. Alavi Jan 2005

A Method For Solving Fuzzy Linear Systems, S. Abbasbandy, M. Alavi

Saeid Abbasbandy

In this paper we present a method for solving fuzzy linear systems by two crisp linear systems. Also necessary and sufficient conditions for existence of solution are given. Some numerical examples illustrate the efficiency of the method.


A New Method For Solving Symmetric Fuzzy Linear Systems, S. Abbasbandy, M. Alavi Jan 2005

A New Method For Solving Symmetric Fuzzy Linear Systems, S. Abbasbandy, M. Alavi

Saeid Abbasbandy

In this paper we represent a new method for solving a symmetric fuzzy linear system by two crisp linear systems. Also necessary and sufficient conditions for the solution existence are given.