Taking partially coherent cosh-Gaussian (ChG) beams as an example of more general partially coherent beams, we have studied the spectral degree of coherence of partially coherent ChG beams in the far field. It is sh...Taking partially coherent cosh-Gaussian (ChG) beams as an example of more general partially coherent beams, we have studied the spectral degree of coherence of partially coherent ChG beams in the far field. It is shown that, unlike Gaussian Schell-model (GSM) beams, in the strict sense there do not exist two partially coherent ChG beams which can generate far fields with the same spectral degree of coherence. However, under certain conditions it is possible to find two partially coherent ChG beams with the same spectral degree of coherence in the far field.展开更多
Density transition based self-focusing of cosh-Gaussian laser beam in plasma with linear absorption has been studied. The field distribution in the plasma is expressed in terms of beam width parameter, decentered para...Density transition based self-focusing of cosh-Gaussian laser beam in plasma with linear absorption has been studied. The field distribution in the plasma is expressed in terms of beam width parameter, decentered parameter,and linear absorption coefficient. The differential equation for the beam width parameter is solved by following Wentzel–Kramers–Brillouin(WKB) and paraxial approximation through parabolic wave equation approach. The behaviour of beam width parameter with dimensionless distance of propagation is studied at optimum values of plasma density,decentered parameter and with different absorption levels in the medium. The results reveal that these parameters can affect the self-focusing significantly.展开更多
In this paper,a radially polarised cosh-Gaussian laser beam(CGLB)is used to study the electron acceleration produced in vacuum.A highly energetic electron beam can be achieved by a CGLB,even with comparatively low-pow...In this paper,a radially polarised cosh-Gaussian laser beam(CGLB)is used to study the electron acceleration produced in vacuum.A highly energetic electron beam can be achieved by a CGLB,even with comparatively low-powered lasers.The properties of a CGLB cause it to focus earlier,over a shorter duration than a Gaussian laser beam,which makes it suitable for obtaining high energies over small durations.It is found that the energy gained by the electrons strongly depends upon the decentering parameter of the laser profile.It is also observed that for a fixed value of energy gain,if the decentering parameter is increased,then the intensity of the laser field decreases.The dependence of the energy gained by electrons on the laser intensity and the laserspot size is also studied.展开更多
The purpose of this study is to explore the second harmonic generation(SHG)of a high power Cosh-Gaussian beam in cold collisionless plasma.The ponderomotive force causes carrier redistribution from high field to low f...The purpose of this study is to explore the second harmonic generation(SHG)of a high power Cosh-Gaussian beam in cold collisionless plasma.The ponderomotive force causes carrier redistribution from high field to low field region in presence of a Cosh-Gaussian beam thereby producing density gradients in the transverse direction.The density gradients so produced the results in electron plasma wave(EPW)generation at the frequency of the input beam.The EPW interacts with the input beam resulting in the production of 2nd harmonics.WKB and paraxial approximations are employed for obtaining the 2nd order differential equation describing the behavior of the beam’s spot size against normalized distance.The impact of well-established laser-plasma parameters on the behavior of the beam’s spot size and SHG yield are also analyzed.The focusing behavior of the beam and SHG yield is enhanced with an increase in the density of plasma,the radius of the beam and the decentred parameter,and with a decrease in the intensity of the beam.The results of the current problem are really helpful for complete information of laser-plasma interaction physics.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos 10574097 and 10874125)
文摘Taking partially coherent cosh-Gaussian (ChG) beams as an example of more general partially coherent beams, we have studied the spectral degree of coherence of partially coherent ChG beams in the far field. It is shown that, unlike Gaussian Schell-model (GSM) beams, in the strict sense there do not exist two partially coherent ChG beams which can generate far fields with the same spectral degree of coherence. However, under certain conditions it is possible to find two partially coherent ChG beams with the same spectral degree of coherence in the far field.
基金Supported by a Financial Grant from CSIR,New Delhi,India,under Project No.03(1277)/13/EMR-II
文摘Density transition based self-focusing of cosh-Gaussian laser beam in plasma with linear absorption has been studied. The field distribution in the plasma is expressed in terms of beam width parameter, decentered parameter,and linear absorption coefficient. The differential equation for the beam width parameter is solved by following Wentzel–Kramers–Brillouin(WKB) and paraxial approximation through parabolic wave equation approach. The behaviour of beam width parameter with dimensionless distance of propagation is studied at optimum values of plasma density,decentered parameter and with different absorption levels in the medium. The results reveal that these parameters can affect the self-focusing significantly.
文摘In this paper,a radially polarised cosh-Gaussian laser beam(CGLB)is used to study the electron acceleration produced in vacuum.A highly energetic electron beam can be achieved by a CGLB,even with comparatively low-powered lasers.The properties of a CGLB cause it to focus earlier,over a shorter duration than a Gaussian laser beam,which makes it suitable for obtaining high energies over small durations.It is found that the energy gained by the electrons strongly depends upon the decentering parameter of the laser profile.It is also observed that for a fixed value of energy gain,if the decentering parameter is increased,then the intensity of the laser field decreases.The dependence of the energy gained by electrons on the laser intensity and the laserspot size is also studied.
文摘The purpose of this study is to explore the second harmonic generation(SHG)of a high power Cosh-Gaussian beam in cold collisionless plasma.The ponderomotive force causes carrier redistribution from high field to low field region in presence of a Cosh-Gaussian beam thereby producing density gradients in the transverse direction.The density gradients so produced the results in electron plasma wave(EPW)generation at the frequency of the input beam.The EPW interacts with the input beam resulting in the production of 2nd harmonics.WKB and paraxial approximations are employed for obtaining the 2nd order differential equation describing the behavior of the beam’s spot size against normalized distance.The impact of well-established laser-plasma parameters on the behavior of the beam’s spot size and SHG yield are also analyzed.The focusing behavior of the beam and SHG yield is enhanced with an increase in the density of plasma,the radius of the beam and the decentred parameter,and with a decrease in the intensity of the beam.The results of the current problem are really helpful for complete information of laser-plasma interaction physics.