Found 7 results
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2019
Authors: Adhikari L., Zank G. P., and Zhao L.-L.
Title: Does Turbulence Turn off at the Alfvén Critical Surface?
Abstract:

The Parker Solar Probe (PSP) will eventually reach and cross the Alfvén point or surface as it provides us with direct in situ measurements of the solar atmosphere. The Alfvén surface is the location at which the large-scale bulk solar wind speed ${\boldsymbol{U}}$ and the Alfvén speed ${\boldsymbol{V}}$ A are equal, and thus it separates sub-Aflvénic coronal flow $| {\boldsymbol{U}}| \ll | {{\boldsymbol{V}}}_{{\rm{A}}}| $ from super-Alfv. . .
Date: Jan-05-2019 Publisher: The Astrophysical Journal Pages: 26 DOI: 10.3847/1538-4357/ab141c Available at: https://iopscience.iop.org/article/10.3847/1538-4357/ab141c
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Authors: Mann Ingrid, Nouzák Libor, Vaverka Jakub, Antonsen Tarjei, Fredriksen Åshild, et al.
Title: Dust observations with antenna measurements and its prospects for observations with Parker Solar Probe and Solar Orbiter
Abstract:

The electric and magnetic field instrument suite FIELDS on board the NASA Parker Solar Probe and the radio and plasma waves instrument RPW on the ESA Solar Orbiter mission that explore the inner heliosphere are sensitive to signals generated by dust impacts. Dust impacts have been observed using electric field antennas on spacecraft since the 1980s and the method was recently used with a number of space missions to derive dust fluxes. Here, we consider the details of dust impacts, subsequent development of the impact generated plasma and how it produces the measured signals. We describe empirical approaches to characterise the signals and compare these in a qualitative discussion of laboratory simulations to predict signal shapes for spacecraft measurements in the inner solar system. Wh. . .
Date: 12/2019 Publisher: Annales Geophysicae Pages: 1121 - 1140 DOI: 10.5194/angeo-37-1121-2019 Available at: https://www.ann-geophys.net/37/1121/2019/https://www.ann-geophys.net/37/1121/2019/angeo-37-1121-2019.pdf
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2018
Authors: Witze Alexandra
Title: Death-defying NASA mission will make humanity’s closest approach to the Sun
Abstract:

The Parker Solar Probe will dive into the sizzling solar corona to explore its mysteries.


Date: 07/2018 Publisher: Nature Pages: 452 - 453 DOI: 10.1038/d41586-018-05741-6 Available at: http://www.nature.com/articles/d41586-018-05741-6http://www.nature.com/articles/d41586-018-05741-6.pdfhttp://www.nature.com/articles/d41586-018-05741-6http://www.nature.com/articles/d41586-018-05741-6.pdf
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Authors: Stansby D, Horbury T S, and Matteini L
Title: Diagnosing solar wind origins using in situ measurements in the inner heliosphere
Abstract:

Robustly identifying the solar sources of individual packets of solar wind measured in interplanetary space remains an open problem. We set out to see if this problem is easier to tackle using solar wind measurements closer to the Sun than 1 au, where the mixing and dynamical interaction of different solar wind streams is reduced. Using measurements from the Helios mission, we examined how the proton core temperature anisotropy and cross-helicity varied with distance. At 0.3 au there are two clearly separated anisotropic and isotropic populations of solar wind that are not distinguishable at 1 au. The anisotropic population is always Alfvénic and spans a wide range of speeds. In contrast the isotropic population has slow speeds, and contains a mix of Alfvénic wind with constant mass f. . .
Date: 01/2019 Publisher: Monthly Notices of the Royal Astronomical Society Pages: 1706 - 1714 DOI: 10.1093/mnras/sty2814 Available at: https://academic.oup.com/mnras/article/482/2/1706/5142296http://academic.oup.com/mnras/article-pdf/482/2/1706/26330049/sty2814.pdf
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2017
Authors: Howes Gregory G., Klein Kristopher G., and Li Tak Chu
Title: Diagnosing collisionless energy transfer using field–particle correlations: Vlasov–Poisson plasmas
Abstract:

Turbulence plays a key role in the conversion of the energy of large-scale fields and flows to plasma heat, impacting the macroscopic evolution of the heliosphere and other astrophysical plasma systems. Although we have long been able to make direct spacecraft measurements of all aspects of the electromagnetic field and plasma fluctuations in near-Earth space, our understanding of the physical mechanisms responsible for the damping of the turbulent fluctuations in heliospheric plasmas remains incomplete. Here we propose an innovative field-particle correlation technique that can be used to measure directly the secular energy transfer from fields to particles associated with collisionless damping of the turbulent fluctuations. Furthermore, this novel procedure yields information about th. . .
Date: 02/2017 Publisher: Journal of Plasma Physics DOI: 10.1017/S0022377816001197 Available at: https://www.cambridge.org/core/product/identifier/S0022377816001197/type/journal_articlehttps://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022377816001197
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2016
Authors: Malaspina David M., Ergun Robert E., Bolton Mary, Kien Mark, Summers David, et al.
Title: The Digital Fields Board for the FIELDS instrument suite on the Solar Probe Plus mission: Analog and digital signal processing
Abstract:

The first in situ measurements of electric and magnetic fields in the near-Sun environment (< 0.25 AU from the Sun) will be made by the FIELDS instrument suite on the Solar Probe Plus mission. The Digital Fields Board (DFB) is an electronics board within FIELDS that performs analog and digital signal processing, as well as digitization, for signals between DC and 60 kHz from five voltage sensors and four search coil magnetometer channels. These nine input signals are processed on the DFB into 26 analog data streams. A specialized application-specific integrated circuit performs analog to digital conversion on all 26 analog channels simultaneously. The DFB then processes the digital data using a field programmable gate array (FPGA), generating a variety of data products, including dig. . .
Date: 06/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: 5088 - 5096 DOI: 10.1002/2016JA022344 Available at: http://doi.wiley.com/10.1002/2016JA022344http://onlinelibrary.wiley.com/wol1/doi/10.1002/2016JA022344/fullpdf
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2014
Authors: Li T. C., Drake J. F., and Swisdak M.
Title: DYNAMICS OF DOUBLE LAYERS, ION ACCELERATION, AND HEAT FLUX SUPPRESSION DURING SOLAR FLARES
Abstract:

Observations of flare-heated electrons in the corona typically suggest confinement of electrons. The confinement mechanism, however, remains unclear. The transport of coronal hot electrons into ambient plasma was recently investigated by particle-in-cell (PIC) simulations. Electron transport was significantly suppressed by the formation of a highly localized, nonlinear electrostatic potential in the form of a double layer (DL). In this work large-scale PIC simulations are performed to explore the dynamics of DLs in larger systems where, instead of a single DL, multiple DLs are generated. The primary DL accelerates return current electrons, resulting in high velocity electron beams that interact with ambient ions. This forms a Buneman unstable system that spawns more DLs. Trapping of hea. . .
Date: 09/2014 Publisher: The Astrophysical Journal Pages: 7 DOI: 10.1088/0004-637X/793/1/7 Available at: http://stacks.iop.org/0004-637X/793/i=1/a=7?key=crossref.1ff276d1b5e9632b2d52ebb5720bc5e6
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