scholarly journals Relativistic Gaussian laser beam self-focusing in collisional quantum plasmas

2015 ◽  
Vol 33 (3) ◽  
pp. 397-403 ◽  
Author(s):  
S. Zare ◽  
S. Rezaee ◽  
E. Yazdani ◽  
A. Anvari ◽  
R. Sadighi-Bonabi
Keyword(s):  
Laser Beam ◽  
Laser Energy ◽  
Oscillation Amplitude ◽  
Beam Width ◽  
Spot Size ◽  
Collisional Plasma ◽  
Laser Spot ◽  
Quantum Plasma ◽  
Laser Spot Size ◽  
Self Focusing

AbstractPropagation of Gaussian X-ray laser beam is presented in collisional quantum plasma and the beam width oscillation is studied along the propagation direction. It is noticed that due to energy absorption in collisional plasma, the laser energy drops to an amount less than the critical value of the self-focusing effect and consequently, the laser beam defocuses. It is found that the oscillation amplitude of the laser spot size enhances while passing through collisional plasma. For the greater values of collision frequency, the beam width oscillates with higher amplitude and defocuses in a shallower plasma depth. Also, it is realized that in a dense plasma environment, the laser self-focusing occurs earlier with the higher oscillation amplitude, smaller laser spot size and more oscillations.

scholarly journals Self-Focusing of Hermite-Cosh-Gaussian Laser Beams in Plasma under Density Transition

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Manzoor Ahmad Wani ◽  
Niti Kant
Keyword(s):  
Laser Beam ◽  
Plasma Density ◽  
Focal Spot ◽  
Beam Width ◽  
Spot Size ◽  
Laser Beams ◽  
Equation Approach ◽  
Focal Spot Size ◽  
Self Focusing ◽  
Small Spot

Self-focusing of Hermite-Cosh-Gaussian (HChG) laser beam in plasma under density transition has been discussed here. The field distribution in the medium is expressed in terms of beam-width parameters and decentered parameter. The differential equations for the beam-width parameters are established by a parabolic wave equation approach under paraxial approximation. To overcome the defocusing, localized upward plasma density ramp is considered, so that the laser beam is focused on a small spot size. Plasma density ramp plays an important role in reducing the defocusing effect and maintaining the focal spot size up to several Rayleigh lengths. To discuss the nature of self-focusing, the behaviour of beam-width parameters with dimensionless distance of propagation for various values of decentered parameters is examined by numerical estimates. The results are presented graphically and the effect of plasma density ramp and decentered parameter on self-focusing of the beams has been discussed.

scholarly journals Relativistic ponderomotive self-focusing of quadruple Gaussian laser beam in cold quantum plasma

2018 ◽  
Vol 36 (3) ◽  
pp. 353-358 ◽  
Author(s):  
Richa ◽  
Munish Aggarwal ◽  
Harish Kumar ◽  
Ranju Mahajan ◽  
Navdeep Singh Arora ◽  
...  
Keyword(s):  
Refractive Index ◽  
Laser Beam ◽  
Electron Temperature ◽  
Density Perturbation ◽  
Beam Width ◽  
Quantum Plasma ◽  
Gaussian Laser Beam ◽  
Self Focusing ◽  
Linear Differential ◽  
Paraxial Ray

AbstractIn the present paper, we have investigated self-focusing of the quadruple Gaussian laser beam in underdense cold quantum plasma. The non-linearity chosen is associated with the relativistic mass effect that arises due to quiver motion of electron and electron density perturbation caused by ponderomotive force. The non-linearity modifies the plasma frequency in the dielectric function and hence the refractive index of the medium. The focusing/defocusing of the quadruple laser depends on the refractive index of the medium. We have set up non-linear differential equation that controls the beam width parameter by using well-known paraxial ray approximation and Wentzel–Krammers–Brillouin approximation. The effect of intensity parameter and electron temperature is observed on laser beam self-focusing in the presence of cold quantum plasma. From the results, it is revealed that electron temperature and the initial intensity of the laser beam control the profile dynamics of the laser beam.

Laser spot size and scaling laws for laser beam additive manufacturing

2022 ◽  
Vol 73 ◽  
pp. 26-39
Author(s):  
Jordan S. Weaver ◽  
Jarred C. Heigel ◽  
Brandon M. Lane
Keyword(s):  
Additive Manufacturing ◽  
Laser Beam ◽  
Scaling Laws ◽  
Spot Size ◽  
Laser Spot ◽  
Laser Spot Size

scholarly journals Combined effect of relativistic and ponderomotive nonlinearity on self-focusing of Gaussian laser beam in a cold quantum plasma

2016 ◽  
Vol 34 (3) ◽  
pp. 426-432 ◽  
Author(s):  
H. Kumar ◽  
M. Aggarwal ◽  
Richa ◽  
T.S. Gill
Keyword(s):  
Laser Beam ◽  
Beam Width ◽  
Combined Effect ◽  
Quantum Plasma ◽  
Gaussian Laser Beam ◽  
Relativistic Case ◽  
Self Focusing ◽  
Ponderomotive Nonlinearity ◽  
Paraxial Ray ◽  
The Impact

AbstractIn the present paper, we have investigated self-focusing of Gaussian laser beam in relativistic ponderomotive (RP) cold quantum plasma. When de Broglie wavelength of charged particles is greater than or equal to the inter particle distance or equivalently the temperature is less than or equal to the Fermi temperature, quantum nature of the plasma constituents cannot be ignored. In this context, we have reported self-focusing on account of nonlinear dielectric contribution of RP plasma by taking into consideration the impact of quantum effects. We have setup the nonlinear differential equation for the beam-width parameter by paraxial ray and Wentzel Kramers Brillouin approximation and solved it numerically by the Runge Kutta Fourth order method. Our results show that additional self-focusing is achieved in case of RP cold quantum plasma than relativistic cold quantum plasma and classical relativistic case. The pinching effect offered by quantum plasma and the combined effect of relativistic and ponderomotive nonlinearity greatly enhances laser propagation up to 20 Rayleigh lengths.

How to Interpret the Reflected Laser Probe Signal of Multiple Elementary Substructures in Very Deep Submicron Technologies

2013 ◽  
Author(s):  
M.M. Rebaï ◽  
F. Darracq ◽  
D. Lewis ◽  
P. Perdu ◽  
K. Sanchez
Keyword(s):  
Integrated Circuits ◽  
Laser Beam ◽  
Basic Structure ◽  
Spot Size ◽  
Deep Submicron ◽  
Laser Spot ◽  
Probe Signal ◽  
Laser Spot Size ◽  
Laser Probe ◽  
Complex Information

Abstract The constant size reduction of the elementary structures in integrated circuits (ICs) and their increasing complexity pushes laser probing techniques to their limits. For old technologies these techniques were powerful tools in defects detection and internal analysis, but now the major limitations of the laser spot size implies the understanding of the complex information contained in the reflected beam when it covers an area of multiple elementary structures. Knowing the contribution of each elementary structure covered by the laser spot in the reflected laser beam is the key to have a good analysis and interpretation of the probed area. In this paper we will expose the different parameters that modify the intensity of a laser beam and the contribution of a basic structure covered by a big laser spot size as well as the systematic approach we have built to deal with this challenging reflected laser probe signal from multiple elementary substructures in very deep submicron technologies.

scholarly journals Effects of plasma electron temperature and magnetic field on the propagation dynamics of Gaussian laser beam in weakly relativistic cold quantum plasma

2019 ◽  
Vol 37 (4) ◽  
pp. 435-441 ◽  
Author(s):  
Munish Aggarwal ◽  
Vimmy Goyal ◽  
Richa Kashyap ◽  
Harish Kumar ◽  
Tarsem Singh Gill
Keyword(s):  
Magnetic Field ◽  
Laser Beam ◽  
Electron Temperature ◽  
Axial Magnetic Field ◽  
Beam Width ◽  
Plasma Electron ◽  
Quantum Plasma ◽  
Gaussian Laser Beam ◽  
Self Focusing ◽  
Initial Plasma

AbstractSelf-focusing of Gaussian laser beam has been investigated in quantum plasma under the effect of applied axial magnetic field. The nonlinear differential equation has been derived for studying the variations in the beam-width parameter. The effect of initial plasma electron temperature and the axial magnetic field on self-focusing and normalized intensity are studied. Our investigation reveals that normalized intensity increases to tenfolds where quantum effects are dominant. The normalized intensity further increases to twelvefolds on increasing the magnetic field.

scholarly journals Growth of spike in relativistic Gaussian laser beam in a plasma and its effect on third-harmonic generation

2017 ◽  
Vol 35 (1) ◽  
pp. 137-144 ◽  
Author(s):  
N. Ahmad ◽  
S. T. Mahmoud ◽  
G. Purohit
Keyword(s):  
Laser Beam ◽  
Beam Width ◽  
Spot Size ◽  
Main Beam ◽  
Gaussian Laser Beam ◽  
Third Harmonic ◽  
Single Beam ◽  
Self Focusing ◽  
Diffraction Divergence ◽  
Paraxial Ray

AbstractA paraxial ray formalism is developed to study the evolution of an on axis intensity spike on a Gaussian laser beam in a plasma dominated by relativistic and ponderomotive non-linearities. Ion motion is taken to be frozen. A single beam width parameter characterizes the evolution of the spike. The spike introduces two competing influences: diffraction divergence and self-convergence. The former grows with the reduction in spot size of the spike, while the latter depends on the gradient in non-linear permittivity. Parameter δ = (ωpr00/c) a00/(3.5 r00/r01) characterizes the relative importance of the two, where r01 and r00 are the spike and main beam radii, ωp is the plasma frequency, and a00 is the normalized laser amplitude. For δ > 1, the intensity ripple causes faster self-focusing of the beam; higher the ripple amplitude stronger the focusing. In the opposite limit, diffraction divergence increases more rapidly, slowing down the self-focusing of the beam. As the beam intensity rises due to self-focusing, it causes stronger generation of the third harmonic.

scholarly journals Ponderomotive self-focusing of linearly polarized laser beam in magnetized quantum plasma

2016 ◽  
Vol 34 (4) ◽  
pp. 764-771 ◽  
Author(s):  
N. S. Rathore ◽  
P. Kumar
Keyword(s):  
Laser Beam ◽  
Ponderomotive Force ◽  
Density Perturbation ◽  
Spot Size ◽  
High Density ◽  
Intense Laser ◽  
Quantum Plasma ◽  
Quantum Hydrodynamic Model ◽  
Self Focusing ◽  
Linearly Polarized

AbstractPonderomotive non-linearities arising by propagation of a linearly polarized laser beam through high-density quantum plasma are studied. The intense laser beam sets the plasma electrons in quiver motion and consequently ponderomotive non-linearity sets in leading to electron density perturbation inside the plasma. The interaction formalism has been built using the quantum hydrodynamic model. Laser beam traversing through high-density quantum plasma acquires an additional focusing tendency due to the perturbation induced by ponderomotive force in the plasma density. The ponderomotive force causes the beam to focus and the quantum effects contribute in focusing. The transverse magnetization of quantum plasma enhances the self-focusing and increase in magnetic field limits the spot size.

Modelling of the laser spot size dependence of retinal thermal damage

2005 ◽  
Author(s):  
Karl Schulmeister ◽  
Bernhard Seiser ◽  
Florian Edthofer ◽  
David J. Lund
Keyword(s):  
Size Dependence ◽  
Thermal Damage ◽  
Spot Size ◽  
Laser Spot ◽  
Laser Spot Size
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