In agricultural fields, heavy metal contamination is responsible for limiting the crop productivi... more In agricultural fields, heavy metal contamination is responsible for limiting the crop productivity and quality. This study reports that the plants of Brassica juncea L. cv. Pusa bold grown on contaminated substrates [Cu, Cr(VI), As(III), As(V)] under simulated field conditions have shown translocation of metals to the upper part and its sequestration in the leaves without significantly affecting on oil yield, except for Cr and higher concentration of As(V), compared to control. Decrease in the oil content in As(V) treated plants was observed in a dose dependent manner; however, maximum decrease was recorded in Cr treated plants. Among all the metal treatments, Cr was the most toxic as evident from the decrease in oil content, growth parameters and antioxidants. The accumulation of metals was below the detection limit in the seeds grown on 10 and 30 mg kg(-1) As(III) and Cr(VI); 10 mg kg(-1) As(V)) and thus can be recommended only for oil cultivation.
A detailed analytical theory is developed for studying the phenomenon of generation of high ampli... more A detailed analytical theory is developed for studying the phenomenon of generation of high amplitude wakefield using a seed laser pulse and another coaxially propagating, trailing pulse. The two laser pulses are separated by a fixed distance between them and have the same polarization, frequency, length, intensity, and profile. The study shows that the maximum energy gained by the test electron significantly depends upon the distance between the two pulses. Phase space analysis shows that a test electron of significantly lower energy, injected behind the trailing laser pulse, will be trapped and accelerated to higher energy as compared to the single pulse case.
In this paper, evolution of the spot size of an intense laser beam propagating in axially magneti... more In this paper, evolution of the spot size of an intense laser beam propagating in axially magnetized, cold, underdense plasma has been studied. The effect of longitudinal magnetization on the laser spot for a left as well as a right circularly polarized laser beam has been considered. Critical power for nonlinear self-focusing of the beam in magnetized plasma has been obtained.
Propagation characteristics and modulation instability of an intense laser beam propagating in an... more Propagation characteristics and modulation instability of an intense laser beam propagating in an axially tapered plasma channel, having a parabolic radial density profile, are studied. Using the source-dependent expansion technique, the evolution equation for the laser spot is set up and conditions for propagation of the laser beam with a constant spot size (matched beam) are obtained. Further, the dispersion relation and growth rate of modulation instability of the laser pulse as it propagates through linearly and quadratically tapered plasma channels, have been obtained.
When an intense laser pulse interacts with homogeneous plasma embedded in a transverse magnetic f... more When an intense laser pulse interacts with homogeneous plasma embedded in a transverse magnetic field, transverse current density oscillating with frequency twice that of the laser field is set up. This leads to generation of second harmonic radiation with significant conversion efficiency.
The phenomenon of laser plasma coupling is numerically studied by examining the nonlinear coupled... more The phenomenon of laser plasma coupling is numerically studied by examining the nonlinear coupled temporal evolution of plasma wave amplitude in backward stimulated Raman scattering (BSRS). The theoretical model developed for numerical study takes into account the combined effects of relativistic and ponderomotive nonlinearities. The study shows that in BSRS, the phenomenon of nonlinear temporal growth and saturation of plasma waves strongly depends on laser radiation wavelength. This appears in the form of significant changes in saturation amplitude and saturation time of plasma waves excited due to long and short wavelength laser waves.
In this paper, evolution of spot size of an intense laser beam in cold, underdense, magnetized pl... more In this paper, evolution of spot size of an intense laser beam in cold, underdense, magnetized plasma has been studied. The plasma is embedded in a uniform magnetic field perpendicular to both, the direction of propagation and electric vector of the radiation field. Nonlinear current density is set up and the source dependent expansion method is used to determine the evolution of the spot size of a laser beam having a Gaussian profile. It is shown that transverse magnetization of plasma enhances the self-focusing property of the laser beam leading to reduction in critical power required to self-focus the beam.
In agricultural fields, heavy metal contamination is responsible for limiting the crop productivi... more In agricultural fields, heavy metal contamination is responsible for limiting the crop productivity and quality. This study reports that the plants of Brassica juncea L. cv. Pusa bold grown on contaminated substrates [Cu, Cr(VI), As(III), As(V)] under simulated field conditions have shown translocation of metals to the upper part and its sequestration in the leaves without significantly affecting on oil yield, except for Cr and higher concentration of As(V), compared to control. Decrease in the oil content in As(V) treated plants was observed in a dose dependent manner; however, maximum decrease was recorded in Cr treated plants. Among all the metal treatments, Cr was the most toxic as evident from the decrease in oil content, growth parameters and antioxidants. The accumulation of metals was below the detection limit in the seeds grown on 10 and 30 mg kg(-1) As(III) and Cr(VI); 10 mg kg(-1) As(V)) and thus can be recommended only for oil cultivation.
A detailed analytical theory is developed for studying the phenomenon of generation of high ampli... more A detailed analytical theory is developed for studying the phenomenon of generation of high amplitude wakefield using a seed laser pulse and another coaxially propagating, trailing pulse. The two laser pulses are separated by a fixed distance between them and have the same polarization, frequency, length, intensity, and profile. The study shows that the maximum energy gained by the test electron significantly depends upon the distance between the two pulses. Phase space analysis shows that a test electron of significantly lower energy, injected behind the trailing laser pulse, will be trapped and accelerated to higher energy as compared to the single pulse case.
In this paper, evolution of the spot size of an intense laser beam propagating in axially magneti... more In this paper, evolution of the spot size of an intense laser beam propagating in axially magnetized, cold, underdense plasma has been studied. The effect of longitudinal magnetization on the laser spot for a left as well as a right circularly polarized laser beam has been considered. Critical power for nonlinear self-focusing of the beam in magnetized plasma has been obtained.
Propagation characteristics and modulation instability of an intense laser beam propagating in an... more Propagation characteristics and modulation instability of an intense laser beam propagating in an axially tapered plasma channel, having a parabolic radial density profile, are studied. Using the source-dependent expansion technique, the evolution equation for the laser spot is set up and conditions for propagation of the laser beam with a constant spot size (matched beam) are obtained. Further, the dispersion relation and growth rate of modulation instability of the laser pulse as it propagates through linearly and quadratically tapered plasma channels, have been obtained.
When an intense laser pulse interacts with homogeneous plasma embedded in a transverse magnetic f... more When an intense laser pulse interacts with homogeneous plasma embedded in a transverse magnetic field, transverse current density oscillating with frequency twice that of the laser field is set up. This leads to generation of second harmonic radiation with significant conversion efficiency.
The phenomenon of laser plasma coupling is numerically studied by examining the nonlinear coupled... more The phenomenon of laser plasma coupling is numerically studied by examining the nonlinear coupled temporal evolution of plasma wave amplitude in backward stimulated Raman scattering (BSRS). The theoretical model developed for numerical study takes into account the combined effects of relativistic and ponderomotive nonlinearities. The study shows that in BSRS, the phenomenon of nonlinear temporal growth and saturation of plasma waves strongly depends on laser radiation wavelength. This appears in the form of significant changes in saturation amplitude and saturation time of plasma waves excited due to long and short wavelength laser waves.
In this paper, evolution of spot size of an intense laser beam in cold, underdense, magnetized pl... more In this paper, evolution of spot size of an intense laser beam in cold, underdense, magnetized plasma has been studied. The plasma is embedded in a uniform magnetic field perpendicular to both, the direction of propagation and electric vector of the radiation field. Nonlinear current density is set up and the source dependent expansion method is used to determine the evolution of the spot size of a laser beam having a Gaussian profile. It is shown that transverse magnetization of plasma enhances the self-focusing property of the laser beam leading to reduction in critical power required to self-focus the beam.
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Papers by Rohit Mishra