The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Fugen Zhou - One of the best experts on this subject based on the ideXlab platform.
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angle of arrival fluctuations considering turbulence outer scale for optical waves propagation through moderate to strong non Kolmogorov turbulence
Journal of The Optical Society of America A-optics Image Science and Vision, 2014Co-Authors: Fugen ZhouAbstract:Based on the generalized von Karman spectrum and the extended Rytov theory, new analytic expressions for the variance of angle of arrival (AOA) fluctuations are derived for optical plane and spherical waves propagating through moderate-to-strong non-Kolmogorov turbulence with horizontal path. They consider finite turbulence outer scale and general spectral power law value, and cover a wide range of non-Kolmogorov turbulence strength. When the turbulence outer scale is set to infinite, the new expressions can reduce correctly to previously published analytic expressions [J. Opt. Soc. Am. A, 302188 (2013]. The final results show that the increased turbulence outer scale value enlarges the variance of AOA fluctuations greatly under moderate-to-strong (or strong) non-Kolmogorov turbulence.
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irradiance scintillation for gaussian beam wave propagating through weak non Kolmogorov turbulence
Optics Express, 2011Co-Authors: Linyan Cui, Bindang Xue, Lei Cao, Shiling Zheng, Wenfang Xue, Xiangzhi Bai, Xiaoguang Cao, Fugen ZhouAbstract:Kolmogorov turbulence theory based models cannot be directly applied in non-Kolmogorov turbulence case, which has been reported recently by increasing experimental evidence and theoretical investigation. In this study, based on the generalized von Karman spectral model, the theoretical expression of the irradiance scintillation index is derived for Gaussian-beam wave propagating through weak non-Kolmogorov turbulence with horizontal path. In the derivation, the expression is divided into two parts for physical analysis purpose and mathematical analysis convenience. This expression considers the influences of finite turbulence inner and outer scales and has a general spectral power law value in the range 3 to 4 instead of standard power law value of 11/3 (for Kolmogorov turbulence). Numerical simulations are conducted to investigate the influences.
Shiyong Huang - One of the best experts on this subject based on the ideXlab platform.
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on the existence of the Kolmogorov inertial range in the terrestrial magnetosheath turbulence
The Astrophysical Journal, 2017Co-Authors: Shiyong Huang, Lina Hadid, F Sahraoui, Zhigang Yuan, Xinfa DengAbstract:In the solar wind, power spectral density (PSD) of the magnetic field fluctuations generally follow the so-called Kolmogorov spectrum f −5/3 in the inertial range, where the dynamics is thought to be dominated by nonlinear interactions between counter-propagating incompressible Alfven wave parquets. These features are thought to be ubiquitous in space plasmas. The present study gives a new and more complex picture of magnetohydrodynamic (MHD) turbulence as observed in the terrestrial magnetosheath. The study uses three years of in situ data from the Cluster mission to explore the nature of the magnetic fluctuations at MHD scales in different locations within the magnetosheath, including flanks and subsolar regions. It is found that the magnetic field fluctuations at MHD scales generally have a PSD close to f −1 (shallower than the Kolmogorov one f −5/3) down to the ion characteristic scale, which recalls the energy-containing scales of solar wind turbulence. The Kolmogorov spectrum is observed only away from the bow shock toward the flank and the magnetopause regions in 17% of the analyzed time intervals. Measuring the magnetic compressibility, it is shown that only a fraction (35%) of the observed Kolmogorov spectra was populated by shear Alfvenic fluctuations, whereas the majority of the events (65%) was found to be dominated by compressible magnetosonic-like fluctuations, which contrasts with well-known turbulence properties in the solar wind. This study gives a first comprehensive view of the origin of the f −1 and the transition to the Kolmogorov inertial range; both questions remain controversial in solar wind turbulence.
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on the existence of the Kolmogorov inertial range in the terrestrial magnetosheath turbulence
arXiv: Space Physics, 2016Co-Authors: Shiyong Huang, Lina Hadid, F Sahraoui, Zhigang Yuan, Xinfa DengAbstract:In the solar wind, power spectral density (PSD) of the magnetic field fluctuations generally follow the so-called Kolmogorov spectrum f^-5/3 in the inertial range, where the dynamics is thought to be dominated by nonlinear interactions between counter-propagating incompressible Alfven wave parquets. These features are thought to be ubiquitous in space plasmas. The present study gives a new and more complex picture of magnetohydrodynamics (MHD) turbulence as observed in the terrestrial magnetosheath. The study uses three years of in-situ data from the Cluster mission to explore the nature of the magnetic fluctuations at MHD scales in different locations within the magnetosheath, including flanks and subsolar regions. It is found that the magnetic field fluctuations at MHD scales generally have a PSD close to f^-1 (shallower than the Kolmogorov one f^-5/3) down to the ion characteristic scale, which recalls the energy containing scales of solar wind turbulence. The Kolmogorov spectrum is observed only away from the bow shock toward the flank and the magnetopause regions in 17% of the analyzed time intervals. Measuring the magnetic compressibility, it is shown that only a fraction (35%) of the observed Kolmogorov spectra were populated by shear Alfvenic fluctuations, whereas the majority of the events (65%) was found to be dominated by compressible magnetosonic-like fluctuations, which contrasts with well-known turbulence properties in the solar wind. This study gives a first comprehensive view of the origin of the f^-1 and the transition to the Kolmogorov inertial range; both questions remain controversial in solar wind turbulence.
Liying Tan - One of the best experts on this subject based on the ideXlab platform.
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temporal power spectrum of irradiance fluctuations for a gaussian beam wave propagating through non Kolmogorov turbulence
Optics Express, 2015Co-Authors: Liying Tan, Chao ZhaiAbstract:In the past decades, both the increasing experimental evidence and some results of theoretical investigation on non-Kolmogorov turbulence have been reported. This has prompted the study of optical propagation in non-Kolmogorov atmospheric turbulence. In this paper, based on the thin phase screen model and a non-Kolmogorov power spectrum which owns a generalized power law instead of standard Kolmogorov power law value 11/3 and a generalized amplitude factor instead of constant value 0.033, the temporal power spectrum of irradiance fluctuations for a Gaussian-beam wave is derived in the weak fluctuation regime for a horizontal path. The analytic expressions are obtained and then used to analyze the influence of spectral power law variations on the temporal power spectrum of irradiance fluctuations.
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temporal frequency spectra for optical wave propagating through non Kolmogorov turbulence
Optics Express, 2010Co-Authors: Liying Tan, Yijun JiangAbstract:Nowadays it has been accepted that the Kolmogorov model is not the only possible turbulent one in the atmosphere, which has been confirmed by the increasing experimental evidences and some results of theoretical investigation. This has prompted the scientist community to study optical propagation in non-Kolmogorov atmospheric turbulence. In this paper, using a non-Kolmogorov power spectrum which has a more general power law instead of standard Kolmogorov power law value 11/3 and a more general amplitude factor instead of constant value 0.033, the temporal power spectra of the presentative amplitude and phase effects, irradiance and angle of arrival fluctuations, have been derived for horizontal link in weak turbulence. And then the influence of spectral power-law variations on the temporal power spectrum has been analyzed. It is anticipated that this work is helpful to the investigations of atmospheric turbulence and optical wave propagation in the atmospheric turbulence.
Xinfa Deng - One of the best experts on this subject based on the ideXlab platform.
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on the existence of the Kolmogorov inertial range in the terrestrial magnetosheath turbulence
The Astrophysical Journal, 2017Co-Authors: Shiyong Huang, Lina Hadid, F Sahraoui, Zhigang Yuan, Xinfa DengAbstract:In the solar wind, power spectral density (PSD) of the magnetic field fluctuations generally follow the so-called Kolmogorov spectrum f −5/3 in the inertial range, where the dynamics is thought to be dominated by nonlinear interactions between counter-propagating incompressible Alfven wave parquets. These features are thought to be ubiquitous in space plasmas. The present study gives a new and more complex picture of magnetohydrodynamic (MHD) turbulence as observed in the terrestrial magnetosheath. The study uses three years of in situ data from the Cluster mission to explore the nature of the magnetic fluctuations at MHD scales in different locations within the magnetosheath, including flanks and subsolar regions. It is found that the magnetic field fluctuations at MHD scales generally have a PSD close to f −1 (shallower than the Kolmogorov one f −5/3) down to the ion characteristic scale, which recalls the energy-containing scales of solar wind turbulence. The Kolmogorov spectrum is observed only away from the bow shock toward the flank and the magnetopause regions in 17% of the analyzed time intervals. Measuring the magnetic compressibility, it is shown that only a fraction (35%) of the observed Kolmogorov spectra was populated by shear Alfvenic fluctuations, whereas the majority of the events (65%) was found to be dominated by compressible magnetosonic-like fluctuations, which contrasts with well-known turbulence properties in the solar wind. This study gives a first comprehensive view of the origin of the f −1 and the transition to the Kolmogorov inertial range; both questions remain controversial in solar wind turbulence.
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on the existence of the Kolmogorov inertial range in the terrestrial magnetosheath turbulence
arXiv: Space Physics, 2016Co-Authors: Shiyong Huang, Lina Hadid, F Sahraoui, Zhigang Yuan, Xinfa DengAbstract:In the solar wind, power spectral density (PSD) of the magnetic field fluctuations generally follow the so-called Kolmogorov spectrum f^-5/3 in the inertial range, where the dynamics is thought to be dominated by nonlinear interactions between counter-propagating incompressible Alfven wave parquets. These features are thought to be ubiquitous in space plasmas. The present study gives a new and more complex picture of magnetohydrodynamics (MHD) turbulence as observed in the terrestrial magnetosheath. The study uses three years of in-situ data from the Cluster mission to explore the nature of the magnetic fluctuations at MHD scales in different locations within the magnetosheath, including flanks and subsolar regions. It is found that the magnetic field fluctuations at MHD scales generally have a PSD close to f^-1 (shallower than the Kolmogorov one f^-5/3) down to the ion characteristic scale, which recalls the energy containing scales of solar wind turbulence. The Kolmogorov spectrum is observed only away from the bow shock toward the flank and the magnetopause regions in 17% of the analyzed time intervals. Measuring the magnetic compressibility, it is shown that only a fraction (35%) of the observed Kolmogorov spectra were populated by shear Alfvenic fluctuations, whereas the majority of the events (65%) was found to be dominated by compressible magnetosonic-like fluctuations, which contrasts with well-known turbulence properties in the solar wind. This study gives a first comprehensive view of the origin of the f^-1 and the transition to the Kolmogorov inertial range; both questions remain controversial in solar wind turbulence.
Wenhe Du - One of the best experts on this subject based on the ideXlab platform.
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outer scale effect of a gaussian beam wave propagated through non Kolmogorov turbulent atmosphere on the beam wander
Journal of Russian Laser Research, 2020Co-Authors: Wenhe Du, Zhanyu Yang, Yanchun Wang, Yuan Ti, Danjie Jiao, Chen ChenAbstract:To date, it is a common knowledge that there exists two kinds of turbulence in Earth’s aerosphere, the Kolmogorov turbulence and the non-Kolmogorov turbulence, which has been confirmed by both increasing experimental evidences and some results of theoretical investigations. Therefore, it is necessary to further develop theory of optical wave propagation through the atmospheric turbulence, namely, to study the propagation of laser beams in the non-Kolmogorov turbulence before analyzing the joint influence of the Kolmogorov turbulence and the non-Kolmogorov turbulence on satellite laser communication. Also it is well known that the beam wander results in the performance degradation of satellite laser communication systems and exert an influence on the achievement and stability of its links. In this paper, considering a non-Kolmogorov generalized exponential power spectrum of refractive-index fluctuations, we derive the variances of beam wander for a Gaussian-beam wave in weak turbulence for a horizonal path. This spectrum includes the inner and outer scales with a generalized power law; thus, we also analyze the effect of spectral power law and outer scale variations on the beam wander. It is important to note that the expression for the beam wander variance obtained is concise closed form and independent on the optical wavelength.
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log amplitude variance for a gaussian beam wave propagating through non Kolmogorov turbulence
Optics Express, 2010Co-Authors: Wenhe Du, Siyuan YuAbstract:In the past decades, both the increasing experimental evidences and some results of theoretical investigation on non-Kolmogorov turbulence have been reported. This has prompted the study of optical propagation in non-Kolmogorov atmospheric turbulence. In this paper, using a non-Kolmogorov power spectrum which owns a generalized power law instead of standard Kolmogorov power law value 11/3 and a generalized amplitude factor instead of constant value 0.033, the log-amplitude variances for a Gaussian-beam wave are derived in the weak-fluctuation regime for a horizonal path. The analytic expressions are obtained and then used to analyze the effect of spectral power-law variations on the log-amplitude fluctuations of Gaussian-beam wave.
