scholarly journals A Mathematical Modelling with Zakharov System for Langmuir Wave in Unmagnetized Plasma

2020 ◽  
Vol 3 (11) ◽  
pp. 134-136
Author(s):  
Sudarshan Kumar Chakravarti
Keyword(s):  
Ponderomotive Force ◽  
Langmuir Wave ◽  
Vital Role ◽  
The Self ◽  
Beam Radius ◽  
Zakharov System ◽  
Focusing Effect ◽  
Relativistic Mass ◽  
Self Focusing ◽  
Unmagnetized Plasma

In this article we present a discussion and overview of mathematical result of the self-focusing of a Langmuir wave which governs Zakharov system and has studied the self- focusing of a Langmuir wave following by Gaussian distribution. Langmuir wave propagates through uncharged plasma which governed by Zakharov systems. The phenomenon plays a vital role in the Dynamics. We present the article mathematical model with effect of Landou damping. Relativistic mass oscillation and ponderomotive force on electrons of the ionized plasma encouraged the Langmuir wave which resists the self-focusing effect when damping is ignored. The Beam radius gets narrow. when it further propagates considering the paraxial ray’s approximation, the self-focusing length Rn. It shows that characteristics of varying bandwidth distance of propagation in relativistic plasma.

Asymmetric self-focusing of a laser pulse in plasma

2002 ◽  
Vol 68 (1) ◽  
pp. 75-80 ◽  
Author(s):  
A. UPADHYAY ◽  
V. K. TRIPATHI ◽  
A. K. SHARMA ◽  
H. C. PANT
Keyword(s):  
Short Pulse ◽  
The Self ◽  
Combined Effects ◽  
Mass Variation ◽  
Focusing Effect ◽  
Low Intensity ◽  
Short Pulse Laser ◽  
Relativistic Mass ◽  
Self Focusing ◽  
Pulse Distortion

An intense short-pulse laser propagating through a plasma undergoes self-pulse distortion due to the combined effects of nonlinearity-induced self-focusing and dispersion. The nonlinearity arises as a result of relativistic mass variation. The low-intensity front of the pulse converges mildly, while the high-intensity later portions self-focus strongly. However, at the intensity maxima, the self-focusing effect is masked by the saturation effect of the nonlinear refractive index. The group velocity is also a function of intensity; as a result, the front of the pulse becomes sharpened, while the tail tends to be broadened.

scholarly journals Self focusing of a laser pulse in plasma with periodic density ripple

2009 ◽  
Vol 27 (2) ◽  
pp. 193-199 ◽  
Author(s):  
Sukhdeep Kaur ◽  
A.K. Sharma
Keyword(s):  
Laser Pulse ◽  
Spot Size ◽  
High Plasma ◽  
The Self ◽  
Intense Laser ◽  
Wave Number ◽  
Plasma Parameters ◽  
Density Region ◽  
Focusing Effect ◽  
Self Focusing

AbstractPropagation of an intense laser pulse in plasma with a periodically modulated density is considered using envelope equations. The laser induces modifications of the plasma refractive indexviarelativistic and ponderomotive nonlinearities. In the region of high plasma density, the self focusing effect of nonlinearity suppresses the diffraction divergence, and the laser converges. As the beam enters into the low density region, the diffraction tends to diverge it offsetting the convergence due to the curvature it has acquired. For a given set of plasma parameters, there is a critical power of the laser above which it propagates in a periodically focused manner. Below this power the laser undergoes overall divergence. At substantially higher powers, the laser beam continues to converge until the saturation effect of nonlinearity suppresses the self focusing and diffraction predominates. The effect of density ripple is to cause overall increase in the self focusing length. The minimum spot size decreases with the wave number of the ripple.

scholarly journals The Influence of the Self-focusing Effect on the Optical Force Acting on Dielectric Particle Embedded in Kerr Medium

2013 ◽  
Vol 23 (2) ◽  
pp. 155
Author(s):  
Hoang Van Nam ◽  
Cao Thanh Le ◽  
Ho Quang Quy
Keyword(s):  
Refractive Index ◽  
Nonlinear Coefficient ◽  
Optical Tweezer ◽  
Optical Force ◽  
The Self ◽  
Stable Region ◽  
Kerr Medium ◽  
Optical Forces ◽  
Focusing Effect ◽  
Self Focusing

The influence of the self-focusing effect arised from Kerr effect on the optical force acting on the dielecric particle embedded in the Kerr medium, which is irradiated by the Gaussian beam, is proposed to concern. The expressions of the optical forces with the nonlinear refractive index and nonlinear focal length are derived. Using them, the distribution of the optical forces in the trapping region of the optical tweezer is simulated and discussed for same distinguished case of the Kerr medium with different nonlinear coefficients. The results show that the stabe region of the optical tweezer depends on the nonlinear coefficient of refractive index. Moreover, the stable region could be brokendown with a critical value of the nonlinear coefficient of refractive index of the surrounding medium irradiated by Gaussian laser pulse described by given parameters as  intensity, duration and radius of beam waist. 

scholarly journals The self-focusing condition of a charged particle beam in a resistive plasma

2021 ◽  
Vol 87 (5) ◽  
Author(s):  
Xiao-Chuan Ning ◽  
Tian-Yi Liang ◽  
D. Wu ◽  
Zheng-Mao Sheng
Keyword(s):  
Charged Particle ◽  
Plasma Heating ◽  
Particle Beam ◽  
The Self ◽  
Beam Radius ◽  
Charged Particle Beam ◽  
Beam Focusing ◽  
Self Focusing ◽  
Focusing Distance ◽  
Resistive Plasma

The self-focusing condition of a charged particle beam in a resistive plasma has been studied. When plasma heating is weak, the beam focusing is intensified by increasing the beam density or velocity. However, when plasma heating is strong, the beam focusing is only determined by the beam velocity. Especially, in weak heating conditions, the beam trends to be focused into the centre as a whole, and in strong heating conditions, a double-peak structure with a hollow centre is predicted to appear. Furthermore, it is found that the beam radius has a significant effect on focusing distance: a larger the beam radius will result in a longer focusing distance. Simulation results also show that when the beam radius is large enough, filamentation of the beam appears. Our results will serve as a reference for relevant beam–plasma experiments and theoretical analyses, such as heavy ion fusion and ion-beam-driven high energy density physics.

The self-focusing effect

1973 ◽  
Vol 111 (10) ◽  
pp. 249 ◽  
Author(s):  
G.A. Askar'yan
Keyword(s):  
The Self ◽  
Focusing Effect ◽  
Self Focusing

scholarly journals Relativistic and ponderomotive self-focusing of a laser pulse in magnetized plasma

2012 ◽  
Vol 30 (4) ◽  
pp. 659-664 ◽  
Author(s):  
Anamika Sharma ◽  
V.K. Tripathi
Keyword(s):  
Laser Pulse ◽  
Cyclotron Frequency ◽  
Ponderomotive Force ◽  
Beam Width ◽  
Laser Frequency ◽  
Electron Cyclotron ◽  
The Self ◽  
Magnetized Plasma ◽  
Electron Cyclotron Frequency ◽  
Self Focusing

AbstractThe self-focusing of an intense right circularly polarized Gaussian laser pulse in magnetized plasma is studied. The ions are taken to be immobile and relativistic mass effect is incorporated in both the plasma frequency (ωp) and the electron cyclotron frequency (ωc) while determining the ponderomotive force on electrons. The ponderomotive force causes electron expulsion when the effective electron cyclotron frequency is below twice the laser frequency. The nonlinear plasma dielectric function due to ponderomotive and relativistic effects is derived, which is then employed in beam-width parameter equation to study the self-focusing of the laser beam. From this, we estimate the importance of relativistic self-focusing in comparison with ponderomotive self-focusing at moderate laser intensities. The beam width parameter decreases with magnetic field indicating better self-focusing. When the laser intensity is very high, the relativistic gamma factor can be modeled as ${\rm \gamma} = 0.8\left({{{{\rm \omega} _c } / {\rm \omega} }} \right)+ \sqrt {1 + a_0^2 }$γ=0.8(ωc/ω)+1+a02 where ω and a0 are the laser frequency and the normalized laser field strength, respectively. The cyclotron effects on the self-focusing of laser pulse are reduced at high field strengths.

scholarly journals Self-Focusing Property of Partially Coherent Beam With Non-Uniform Correlation Structure in Non-Linear Media

2022 ◽  
Vol 9 ◽  
Author(s):  
Lu Lu ◽  
Zhiqiang Wang ◽  
Jiayi Yu ◽  
Chunhong Qiao ◽  
Rong Lin ◽  
...  
Keyword(s):  
Beam Width ◽  
Vital Role ◽  
Coherent Beam ◽  
The Self ◽  
Correlation Structure ◽  
Threshold Condition ◽  
Partially Coherent ◽  
Self Focusing ◽  
Non Linear ◽  
Focusing Property

Coherence in a light beam has the potential to serve as a degree of freedom for manipulating the beam. In this work, the self-focusing property of a partially coherent beam with a non-uniform correlation structure propagating in a non-linear medium is investigated. The analysis of the evolution of beam width reveals that the coherence structure plays a vital role in the self-focusing formation. A threshold condition for the coherence radius is proposed for the first time, and the relation of self-focusing length and initial coherence radius is studied numerically and analytically. It is shown that a feasible approach for manipulating the self-focusing length by adjusting the initial coherence radius is achieved.

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