The outer scale of solar-wind turbulence from GALILEO coronal-sounding data

Ефимов, А. И.; Чашей, И. В.; Samoznaev, L. N.; Andreev, V. E.; Bird, M. K.; Edenhofer, P.; Plettemeier, Dirk; Wohlmuth, R.

doi:10.1134/1.1495034

Cited by 18 publications

(3 citation statements)

References 17 publications

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“…Observationally, detection of density fluctuations beyond the base of corona relies largely on transcoronal radio sensing techniques. The geometric considerations and general experimental paradigm for these methods are well documented (Tyler et al, 1981;Chashei et al, 2005;Yakovlev and Pisanko, 2018;Bird and Edenhofer, 1990;Efimov et al, 2002). Density fluctuations across the sensing radio path (line-of-sight, LOS) induce frequency fluctuations (FF) at the receiving radio telescope due to a changing index of refraction associated with the electron density disturbances.…”

Section: Introductionmentioning

confidence: 99%

Coronal Electron Density Fluctuations Inferred from Akatsuki Spacecraft Radio Observations

et al. 2020

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Trans-coronal radio observations were taken during the 2011 observing campaign of the Akatsuki spacecraft through superior conjunction. The observed X-band (8.4 GHz) signals exhibit frequency fluctuations (FF) that are produced by temporal variations in electron density along the radio ray path. A two-component model for interpretation of the FF is proposed: FF scales largely with acoustic wave amplitude through the inner coronal regions where the sound speed dwarfs the solar wind outflow speed, while FF in the region of solar wind acceleration is dominated by the increased density oscillation frequency on the sensing path that results from bulk advection of the plasma inhomogeneities. An estimate of fractional electron density fluctuation is obtained from the mid-corona. A radial profile of slow solar wind speed is determined in the extended corona using mass-flux continuity principles. The coronal sonic point for slow solar wind is estimated to range from 4 to 5 solar radii from the heliocenter.

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Section: Introductionmentioning

confidence: 99%

Coronal Electron Density Fluctuations Inferred from Akatsuki Spacecraft Radio Observations

et al. 2020

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“…Not only do the data on plasma inhomogeneities provide a deeper understanding of the physical processes occurring in the corona and interplanetary space (Coles and Harmon, 1989;Efimov et al, 2002), but they furnish a means of more rigorously investigating the influence of coronal turbulence on observed characteristics of emission from solar radio sources (Bastian, 1994;Uralov, 1998;Afanasiev, 2006;Afanasiev and Altyntsev, 2006).…”

Section: Introductionmentioning

confidence: 97%

Diagnostics of Near-Solar Plasma Turbulence Parameters Using the Radio Sounding Technique at Small Heliocentric Distances

Afanasiev

2007

Sol Phys

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We investigate the temporal correlation function and the mean intensity of monochromatic radio emission in the neighborhood of a regular caustic produced by radio sounding of near-solar plasma. Using asymptotic analysis and numerical simulation, we determine conditions under which the temporal correlation function is related to the temporal structure function by a relation similar to that used for the solar wind diagnostics Harmon, Astrophys. J. 337, 1023, 1989) in the case of weak refraction of radio waves. Information on the correlation function and on the mean intensity in the caustic shadow region can be used to determine the parameters of the electron density fluctuation spectrum at small heliocentric distances.

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“…Since the radio signals of spacecraft can enter the challenging inner solar wind within 10 solar radii (Rs, 1 Rs = 695,700 km), solar conjunction observation of deep-space probes is a common research method to study the coronal structure. This technique was used by Akatsuki to show the difference in the solar-wind velocity between fast and slow winds (Chiba et al 2022), by Galileo to study the outer turbulence scale of the solar wind (Efimov et al 2002), by Venus Express to detect the strong turbulence regions in the super corona (Efimov et al 2021), by Mars Express to study the interplanetary plasma scintillation between the years 2013(Molera Calvés et al 2017Kummamuru et al 2023), by the Mercury Surface, Space Environment, Geochemistry, and Ranging spacecraft to study radio Faraday rotation through a CME (Jensen et al 2018), and in Tianwen-1 (TW1) to detect the oscillation and propagation of the nascent dynamic solar wind structure (Ma et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Application of the Tianwen-1 DOR Signals Observed by Very Long Baseline Interferometry Radio Telescopes in the Study of Solar Wind Plasma and a Coronal Mass Ejection

Wang,

Ma,

Liu

et al. 2023

ApJS

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The Tianwen-1 (TW1) Mars probe experienced solar conjunction for the first time in 2021. The China VLBI Network (CVN) observes the differential one-way ranging (DOR) signals of TW1 throughout its phase. This paper explores the application of CVN observation data to study the solar wind plasma. First, the frequency and phase of the DOR carrier and sidetones at each station are calculated using the Doppler method. Then, the variations in both the differential phase delays (DPD) and the total electron content (TEC) are calculated using the phase of the sidetones. We also statistically analyze the fluctuations in the Delta-DOR (ΔDOR) group delay. The results indicate that the fluctuations of the frequency, phase, ΔDOR group delay, delay rate, and TEC variations of the TW1 signals increase with the decrease of the heliocentric distance. On 2021 November 2, a coronal mass ejection (CME) passed across the ray paths of the telescope beams, when the heliocentric distance and heliographic latitude of the projected position of Mars were 30.6 Rs and 3°, respectively. Our data catch the impact of the CME on the DOR signals. The change of the DPD reaches 170 ps, which is equivalent to 986 TECU. We utilize the cross correlation to analyze the frequency fluctuations at multiple stations, and obtain the propagation direction and velocity variations of the CME. Our analysis indicates that multifrequency DOR signals observed by very long baseline interferometry stations have great application to characterize the electron density variations and propagation of the solar wind plasma.

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The outer scale of solar-wind turbulence from GALILEO coronal-sounding data

Cited by 18 publications

References 17 publications

Coronal Electron Density Fluctuations Inferred from Akatsuki Spacecraft Radio Observations

Coronal Electron Density Fluctuations Inferred from Akatsuki Spacecraft Radio Observations

Diagnostics of Near-Solar Plasma Turbulence Parameters Using the Radio Sounding Technique at Small Heliocentric Distances

Application of the Tianwen-1 DOR Signals Observed by Very Long Baseline Interferometry Radio Telescopes in the Study of Solar Wind Plasma and a Coronal Mass Ejection

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