scholarly journals Parametric Instabilities in a Magnetized Plasma

1982 ◽  
Vol 35 (4) ◽  
pp. 409
Author(s):  
Bhimsen K Shivamoggi
Keyword(s):  
Magnetic Field ◽  
Pump Wave ◽  
Stimulated Raman Scattering ◽  
Brillouin Scattering ◽  
Magnetized Plasma ◽  
Stimulated Scattering ◽  
Electromagnetic Pump ◽  
Background Magnetic Field ◽  
Parametric Instabilities ◽  
Stimulated Brillouin

This paper makes a study of stimulated Raman scattering and stimulated Brillouin scattering of an incident electromagnetic pump wave in a magnetized plasma. The background magnetic field is taken to be parallel to the pump electric field. The growth rates of the two stimulated-scattering instabilities are found to be reduced in the presence of the background magnetic field.

scholarly journals SRS characteristics and its influence on SBS pulse compression in a fluorocarbon liquid

2017 ◽  
Vol 35 (1) ◽  
pp. 114-119 ◽  
Author(s):  
H. Yuan ◽  
Y. Wang ◽  
Z. Lu ◽  
Z. Liu ◽  
Z. Bai ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Pulse Compression ◽  
Laser Intensity ◽  
Stimulated Raman Scattering ◽  
Brillouin Scattering ◽  
Laser System ◽  
Experimental Results ◽  
Frequency Shifts ◽  
Experimental Medium ◽  
Stimulated Brillouin

AbstractIn this paper, the occurrence of the stimulated Raman scattering (SRS) and its effects on stimulated Brillouin scattering (SBS) pulse compression in FC-40 are investigated. As the experimental medium, the characteristics of FC-40 are suitable for pulse compression. Firstly, the frequency shifts and the threshold of SRS in FC-40 are studied with a mode-locked laser system as pump source, without taking the SBS effect into account. On the basis of the experimental results, the competition between SRS and SBS as well as its effect on pulse compression is investigated. Results show that SRS gets higher gain and grows rapidly with the increase of the laser intensity by pump effect, which will result in decreasing of SBS energy reflection.

scholarly journals Effect of the axial magnetic field on coexisting stimulated Raman and Brillouin scattering of a circularly polarized beam

2016 ◽  
Vol 35 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Ashish Vyas ◽  
Swati Sharma ◽  
Ram Kishor Singh ◽  
R.P. Sharma
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Brillouin Scattering ◽  
Wave Interaction ◽  
Scattering Process ◽  
Circularly Polarized ◽  
Polarized Beam ◽  
Stimulated Brillouin ◽  
The Impact ◽  
Stimulated Raman

AbstractThis paper presents a model to study the two prominent coexisting instabilities, stimulated Raman (SRS), and stimulated Brillouin scattering (SBS) in the presence of background axial magnetic field. In the context of laser-produced plasmas, this model is very useful in the situations where a self-generated axial magnetic field is present as well as where an external axial magnetic field is applied. Due to the interplay between both the scattering processes, the behavior of one scattering process is greatly modified in the presence of another coexisting scattering process. The impact of this coexisting phenomenon and axial magnetic field on the back reflectivity of scattered beams has been explored. It has been demonstrated that the back reflectivity gets modified significantly due to the coexistence of both the scattering processes (SRS and SBS) as well as due to the axial magnetic field. Results are also compared with the three-wave interaction case (isolated SRS or SBS case).

Particle acceleration by interstellar plasma shock waves in non-uniform background magnetic field

2020 ◽  
Vol 498 (4) ◽  
pp. 5517-5523
Author(s):  
P Rashed-Mohassel ◽  
M Ghorbanalilu
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Shock Waves ◽  
Electric Field ◽  
Background Field ◽  
Magnetized Plasma ◽  
Background Magnetic Field ◽  
Positive Variation ◽  
Uniform Background ◽  
Plasma Shock

ABSTRACT Particle acceleration by plasma shock waves is investigated for a magnetized plasma cloud propagating in a non-uniform background magnetic field by means of analytical and numerical calculations. The mechanism studied here is mainly, magnetic trapping acceleration (MTA) which is previously investigated for a cloud moving through the uniform interstellar magnetic field (IMF). In this work, the acceleration is studied for a cloud moving in an antiparallel background field with spatial variations along the direction of motion. For negative variation, the cloud moves towards an antiparallel magnetic field with an increasing intensity, the trapped particle moves to locations with higher convective electric field and therefore gains more energy over time. For positive variation, the background field decreases to zero and changes into a parallel field with an increasing intensity. It is concluded that, when the background field vanishes, the MTA mechanism ceases and the particle escapes into the space. This leads to a bouncing acceleration which further increases energy of the gyrating particle. The two processes are followed by a shock drift acceleration, where due to the background magnetic field gradient, the particle drifts along the electric field and gains energy. Although for positive variation, three different mechanisms are involved, energy gain is less than in the case of a uniform background field.

Stimulated Raman backscattering in a magnetized plasma

1978 ◽  
Vol 19 (2) ◽  
pp. 313-324 ◽  
Author(s):  
Joseph E. Willett ◽  
Behrooz Maraghechi
Keyword(s):  
Cold Plasma ◽  
Pump Wave ◽  
Electron Plasma ◽  
Magnetized Plasma ◽  
Threshold Power ◽  
Pump Frequency ◽  
Electron Plasma Wave ◽  
Parametric Decay ◽  
Electromagnetic Pump ◽  
Stimulated Raman Backscattering

The parametric decay of an intense electromagnetic (pump) wave into a back-scattered electromagnetic wave and an electron plasma wave is considered. The dispersion relation for a homogeneous magnetized plasma in the presence of the pump wave is developed in the cold-plasma approximation with the pump frequency large compared to the cyclotron and plasma frequencies. Formulae are derived for the growth rate γ and threshold power PT associated with the instability. The effects of the magnitude and direction of the static magnetic field on γ and PT are studied numerically.

THREE-DIMENSIONAL SIMULATIONS OF STIMULATED BRILLOUIN SCATTERING WITH FOCUSED GAUSSIAN BEAMS

1996 ◽  
Vol 05 (02) ◽  
pp. 387-408 ◽  
Author(s):  
T.R. MOORE ◽  
R.W. BOYD
Keyword(s):  
Pump Wave ◽  
Focal Point ◽  
Brillouin Scattering ◽  
Three Dimensional ◽  
Stokes Wave ◽  
Gaussian Beams ◽  
Spontaneous Noise ◽  
Brillouin Gain ◽  
Dimensional Simulation ◽  
Stimulated Brillouin

We report on a detailed investigation of the process of SBS with focused Gaussian beams via a three-dimensional simulation of the SBS process that includes spontaneous noise. We show that spontaneous noise present at points other than where the initiation of SBS occurs does not significantly affect the Stokes wave. The effects on the Stokes beam of modes not present in the pump wave (nonconjugate modes) are investigated and it is found that the phase of a given Stokes mode is affected by the presence of other modes, a process termed phase pulling. We also show that for a focused Gaussian beam the Brillouin gain parameter does not increase linearly with increased pump power once SBS threshold is reached; rather, above threshold the SBS process resembles a reverse saturable absorber for the pump wave at any point. between the entrance to the medium and the focal point of the pump beam.

Electrostatic Rossby-type ion plasma waves

1988 ◽  
Vol 39 (1) ◽  
pp. 103-114 ◽  
Author(s):  
J. F. McKenzie ◽  
M. K. Dougherty
Keyword(s):  
Magnetic Field ◽  
Rossby Wave ◽  
Vertical Component ◽  
Rotational Frequency ◽  
Rate Of Change ◽  
Magnetized Plasma ◽  
Propagation Mechanism ◽  
Wave Operators ◽  
Geostrophic Balance ◽  
Background Magnetic Field

It is shown that a plasma in which the background magnetic field varies in a direction perpendicular to its line of action can support ‘Rossby-type’ electrostatic waves at frequencies very much less than the ion gyrofrequency. The intrinsic wave propagation mechanism at work is structurally similar to that in the atmospheric Rossby wave, which comes about from fluid perturbations being in quasi-geostrophic equilibrium (i.e. the Coriolis force nearly balances the pressure gradient) and the latitudinal variation of the vertical component of rotational frequency vector (the β-effect) so that the time rate of change of the vertical component of the fluid vorticity is equal to the northward transport of the planetary vorticity. In a plasma this ‘geostrophic balance’ arises from the near-vanishing of the Lorentz force on the ion motion while the β-effect is provided by the transverse spatial variation of the ambient magnetic field. Unlike the atmosphere, however, such a magnetized plasma is capable of supporting two distinct types of Rossby wave. The interesting dispersive and anisotropic features of these waves are revealed by the properties of their wave operators and described in terms of the geometry of their wavenumber surfaces. Since these surfaces intersect, inhomogeneity or nonlinearity will give rise to strong mode-mode coupling in regions where the phases of both modes nearly match.

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