scholarly journals Controlled beat-wave Brillouin scattering in the ionosphere

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
B. Eliasson ◽  
A. Senior ◽  
M. Rietveld ◽  
A. D. R. Phelps ◽  
R. A. Cairns ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Ionospheric Plasma ◽  
Brillouin Scattering ◽  
Scale Model ◽  
Plasma Parameters ◽  
Ion Acoustic Wave ◽  
Electromagnetic Pump ◽  
Pump And Probe ◽  
Ion Acoustic ◽  
Stimulated Brillouin

AbstractStimulated Brillouin scattering experiments in the ionospheric plasma using a single electromagnetic pump wave have previously been observed to generate an electromagnetic sideband wave, emitted by the plasma, together with an ion- acoustic wave. Here we report results of a controlled, pump and probe beat-wave driven Brillouin scattering experiment, in which an ion-acoustic wave generated by the beating of electromagnetic pump and probe waves, results in electromagnetic sideband waves that are recorded on the ground. The experiment used the EISCAT facility in northern Norway, which has several high power electromagnetic wave transmitters and receivers in the radio frequency range. An electromagnetic pump consisting of large amplitude radio waves with ordinary (O) or extraordinary (X) mode polarization was injected into the overhead ionosphere, along with a less powerful probe wave, and radio sideband emissions observed on the ground clearly show stimulated Brillouin emissions at frequencies agreeing with, and changing with, the pump and probe frequencies. The experiment was simulated using a numerical full-scale model which clearly supports the interpretation of the experimental results. Such controlled beat-wave experiments demonstrate a way of remotely investigating the ionospheric plasma parameters.

scholarly journals Stimulated Brillouin backscattering of a ring-rippled laser beam in collisionless plasma

2015 ◽  
Vol 33 (3) ◽  
pp. 499-509 ◽  
Author(s):  
Gunjan Purohit ◽  
Priyanka Rawat
Keyword(s):  
Laser Beam ◽  
Narrow Range ◽  
Brillouin Scattering ◽  
Collisionless Plasma ◽  
Plasma Parameters ◽  
Ion Acoustic Wave ◽  
Coupled Equations ◽  
Ion Acoustic ◽  
Paraxial Ray ◽  
Stimulated Brillouin

AbstractThe effect of the propagation of a ring-rippled laser beam in the presence of relativistic and ponderomotive non-linearities on the excitation of ion-acoustic wave (IAW) and resulting stimulated Brillouin backscattering in collisionless plasma at relativistic powers is studied. To understand the nature of propagation of the ring ripple-like instability, a paraxial-ray approach has been invoked in which all the relevant parameters correspond to a narrow range around the irradiance maximum of the ring ripple. Modified coupled equations for growth of ring ripple in the plasma, generations of IAW and back-stimulated Brillouin scattering (SBS) are derived from fluid equations. These coupled equations are solved analytically and numerically to study the intensity of ring-rippled laser beam and excited IAW as well as back reflectivity of SBS in the plasma for various established laser and plasma parameters. It is found that the back reflectivity of SBS is enhanced due to the strong coupling between ring-rippled laser beam and the excited IAW. The results also show that the back reflectivity of SBS reduce for higher intensity of the laser beam.

scholarly journals Excitation of nonlinear ion acoustic wave and stimulated Brillouin scattering of hollow Gaussian beam in relativistic plasma

2017 ◽  
Vol 35 (2) ◽  
pp. 226-233 ◽  
Author(s):  
P. Sharma
Keyword(s):  
Differential Equation ◽  
Acoustic Wave ◽  
Gaussian Beam ◽  
Brillouin Scattering ◽  
Collisionless Plasma ◽  
Stimulated Brillouin Scattering ◽  
Beam Width ◽  
Ion Acoustic Wave ◽  
Ion Acoustic ◽  
Stimulated Brillouin

AbstractIn the present work, excitation of nonlinear ion acoustic wave (IAW) in collisionless plasma by laser beam having null intensity at the center is examined considering relativistic nonlinearity. The differential equation for beam-width parameter is determined considering relativistic nonlinearity using the paraxial and Wentzel–Kramers–Brillouin approximations by the parabolic equation method. The propagation features of the IAW are found to be modified due to the nonlinearity present in the system. The hollow Gaussian beam (HGB) gets nonlinearly coupled with the seed IAW, results in excitation of nonlinear IAW. The interaction of nonlinear IAW with pump beam demonstrated stimulated Brillouin scattering (SBS) of HGB. It is found that the power of IAW and power of SBS is affected with the order of HGB. The power of IAW and backscattered power of SBS is determined analytically and numerically for various orders of HGB. It is found that the power of IAW and the backscattering is diminished for higher order of HGB.

scholarly journals Stimulated Brillouin backscattering of filamented hollow Gaussian beams

2013 ◽  
Vol 31 (4) ◽  
pp. 689-696 ◽  
Author(s):  
R.P. Sharma ◽  
Ram Kishor Singh
Keyword(s):  
Acoustic Wave ◽  
Gaussian Beam ◽  
Brillouin Scattering ◽  
Collisionless Plasma ◽  
Stimulated Brillouin Scattering ◽  
Ion Acoustic Wave ◽  
Ion Acoustic ◽  
Paraxial Ray ◽  
Stimulated Brillouin ◽  
Plasma Coupling

AbstractThis paper presents an investigation for excitation of ion acoustic wave and resulting stimulated Brillouin scattering in a collisionless plasma due to presence of a laser beam carrying null intensity at center (hollow Gaussian beam). In presence of ponderomotive nonlinearity, the pump beam get focused and affects the back stimulated Brillouin scattering process. To understand the nature of laser plasma coupling, a paraxial-ray approximation has been invoked for the propagation of the hollow Gaussian beam, ion acoustic wave, and stimulated Brillouin scattering. It is observed from the result that self-focusing and back reflectivity reduces for higher order of hollow Gaussian beam.

scholarly journals Determination of the electron temperature in the modified ionosphere over HAARP using the HF pumped Stimulated Brillouin Scatter (SBS) emission lines

2009 ◽  
Vol 27 (12) ◽  
pp. 4409-4427 ◽  
Author(s):  
P. A. Bernhardt ◽  
C. A. Selcher ◽  
R. H. Lehmberg ◽  
S. Rodriguez ◽  
J. Thomason ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Acoustic Wave ◽  
Electric Fields ◽  
Pump Wave ◽  
Scattered Wave ◽  
Matching Condition ◽  
Ion Acoustic Wave ◽  
Matching Conditions ◽  
Ion Acoustic ◽  
Stimulated Brillouin

Abstract. An ordinary mode electromagnetic wave can decay into an ion acoustic wave and a scattered electromagnetic wave by a process called stimulated Brillouin scatter (SBS). The first detection of this process during ionospheric modification with high power radio waves was reported by Norin et al. (2009) using the HAARP transmitter in Alaska. Subsequent experiments have provided additional verification of this process and quantitative interpretation of the scattered wave frequency offsets to yield measurements of the electron temperatures in the heated ionosphere. Using the SBS technique, electron temperatures between 3000 and 4000 K were measured over the HAARP facility. The matching conditions for decay of the high frequency pump wave show that in addition to the production of an ion-acoustic wave, an electrostatic ion cyclotron wave may also be produced by the generalized SBS processes. Based on the matching condition theory, the first profiles of the scattered wave amplitude are produced using the stimulated Brillouin scatter (SBS) matching conditions. These profiles are consistent with maximum ionospheric interactions at the upper-hybrid resonance height and at a region just below the plasma resonance altitude where the pump wave electric fields reach their maximum values.

Stimulated Brillouin backscattering and ion acoustic wave secondary instability

2009 ◽  
Vol 16 (3) ◽  
pp. 032701 ◽  
Author(s):  
B. I. Cohen ◽  
E. A. Williams ◽  
R. L. Berger ◽  
D. Pesme ◽  
C. Riconda
Keyword(s):  
Acoustic Wave ◽  
Secondary Instability ◽  
Ion Acoustic Wave ◽  
Ion Acoustic ◽  
Stimulated Brillouin

Enhanced Brillouin scattering of gaussian laser beam in collisional plasma: Moment theory approach

2014 ◽  
Vol 23 (01) ◽  
pp. 1450011 ◽  
Author(s):  
Keshav Walia
Keyword(s):  
Acoustic Wave ◽  
Laser Beam ◽  
Pump Beam ◽  
Brillouin Scattering ◽  
Scattered Wave ◽  
Theory Approach ◽  
Gaussian Laser Beam ◽  
Moment Theory ◽  
Ion Acoustic Wave ◽  
Ion Acoustic

In the present paper, enhanced Brillouin scattering of a gaussian laser beam in a collisional plasma has been investigated with the help of moment theory approach. The pump wave (ω0, k0) interacts with pre-excited ion-acoustic wave (ω, k), thereby generating a back-scattered wave (ω0 - ω, k0 - k). As a specific case, back scattering for which k ≃ 2k0 has been discussed. Due to nonuniform heating, collisional nonlinearity arises, which leads to redistribution of carriers. As a result background plasma density profile in a direction transverse to pump beam axis is modified. Consequently, the pump beam becomes self-focused and in turn leads focusing of ion-acoustic wave and back-scattered wave under appropriate conditions. It is further observed from the analysis that focusing of waves greatly enhances the SBS back-reflectivity.

scholarly journals Erratum: “Stimulated Brillouin backscattering and ion acoustic wave secondary instability” [Phys. Plasmas 16, 032701 (2009)]

2009 ◽  
Vol 16 (8) ◽  
pp. 089902 ◽  
Author(s):  
B. I. Cohen ◽  
E. A. Williams ◽  
R. L. Berger ◽  
D. Pesme ◽  
C. Riconda
Keyword(s):  
Acoustic Wave ◽  
Secondary Instability ◽  
Ion Acoustic Wave ◽  
Ion Acoustic ◽  
Stimulated Brillouin

scholarly journals Effect of self-focused rippled laser beam on the excitation of ion acoustic wave in relativistic ponderomotive regime

2014 ◽  
Vol 32 (4) ◽  
pp. 557-568 ◽  
Author(s):  
Rakhi Gauniyal ◽  
Prashant Chauhan ◽  
Priyanka Rawat ◽  
Gunjan Purohit
Keyword(s):  
Acoustic Wave ◽  
Laser Beam ◽  
Collisionless Plasma ◽  
Plasma Parameters ◽  
Power Flux ◽  
Ion Acoustic Wave ◽  
Coupled Equations ◽  
Increase With Increase ◽  
Ion Acoustic ◽  
Paraxial Ray

AbstractThis paper presents an investigation of self-focusing of intense Gaussian rippled laser beam in collisionless plasma by including the nonlinearity associated with the relativistic mass and the ponderomotive force and its effects on the excitation of ion acoustic wave. The growth of ripple, riding on an intense Gaussian laser beam in plasma and its coupling with ion acoustic wave has also been studied. Modified coupled equations for main laser beam, growth of laser ripple in plasma, rippled laser beam, beam width, and density perturbation associated with ion acoustic wave are derived using Wentzel-Kramers-Brillouin and paraxial ray approximation. These coupled equations are solved analytically and numerically to study the laser intensity in plasma and the variation of amplitude of the ion acoustic wave for various established laser and plasma parameters. From numerical computation, it is observed that both nonlinearities significantly affected the dynamics of the growth of laser ripple in plasma, propagation of rippled laser beam as well as ion acoustic wave in plasma at high laser power flux. The growth of laser ripple increase with increase in the intensity of laser beam and due to the contribution of growth rate, intensity profile of rippled laser beam and ion acoustic wave modified accordingly.

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