scholarly journals Kinetic-scale Current Sheets in the Solar Wind at 1 au: Properties and the Necessary Condition for Reconnection

2021 ◽  
Vol 923 (1) ◽  
pp. L19
Author(s):  
I. Y. Vasko ◽  
K. Alimov ◽  
T. D. Phan ◽  
S. D. Bale ◽  
F. S. Mozer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Measurements ◽  
Necessary Condition ◽  
Data Set ◽  
Current Sheets ◽  
Background Magnetic Field ◽  
Magnetic Field Measurements ◽  
Wind Spacecraft ◽  
Diamagnetic Drift

Abstract We present a data set and properties of 18,785 proton kinetic-scale current sheets collected over 124 days in the solar wind using magnetic field measurements at 1/11 s resolution aboard the Wind spacecraft. We show that all of the current sheets are in the parameter range where reconnection is not suppressed by diamagnetic drift of the X-line. We argue this necessary condition for magnetic reconnection is automatically satisfied due to the geometry of current sheets dictated by their source, which is the local plasma turbulence. The current sheets are shown to be elongated along the background magnetic field and dependence of the current sheet geometry on local plasma beta is revealed. We conclude that reconnection in the solar wind is not likely to be suppressed or controlled by the diamagnetic suppression condition.

scholarly journals How many solar wind data are sufficient for accurate fluxgate magnetometer offset determinations?

2019 ◽  
Vol 8 (2) ◽  
pp. 285-291 ◽  
Author(s):  
Ferdinand Plaschke
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Measurements ◽  
Wind Data ◽  
Fluxgate Magnetometer ◽  
Time Intervals ◽  
Sensor Position ◽  
Magnetic Field Measurements ◽  
Wind Measurements ◽  
The Magnetic Field

Abstract. Accurate magnetic field measurements by fluxgate magnetometers onboard spacecraft require ground and regular in-flight calibration activities. Therewith, the parameters of a coupling matrix and an offset vector are adjusted; they are needed to transform raw magnetometer outputs into calibrated magnetic field measurements. The components of the offset vector are typically determined by analyzing Alfvénic fluctuations in the solar wind if solar wind measurements are available. These are characterized by changes in the field components, while the magnetic field modulus stays constant. In this paper, the following question is answered: how many solar wind data are sufficient for accurate fluxgate magnetometer offset determinations? It is found that approximately 40 h of solar wind data are sufficient to achieve offset accuracies of 0.2 nT, and about 20 h suffice for accuracies of 0.3 nT or better if the magnetometer offsets do not drift within these time intervals and if the spacecraft fields do not vary at the sensor position. Offset determinations with uncertainties lower than 0.1 nT, however, would require at least hundreds of hours of solar wind data.

scholarly journals Evidence for Plasma Heating at Thin Current Sheets in the Solar Wind

2022 ◽  
Vol 924 (2) ◽  
pp. L22
Author(s):  
Zilu Zhou ◽  
Xiaojun Xu ◽  
Pingbing Zuo ◽  
Yi Wang ◽  
Qi Xu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Plasma Heating ◽  
Magnetic Field Direction ◽  
Current Sheets ◽  
Proton Temperature ◽  
Fast Wind ◽  
Wind Spacecraft ◽  
Slow Wind ◽  
The Magnetic Field

Abstract Plasma heating at thin current sheets in the solar wind is examined using magnetic field and plasma data obtained by the WIND spacecraft in the past 17 years from 2004 to 2019. In this study, a thin current sheet is defined by an abrupt rotation (larger than 45°) of the magnetic field direction in 3 s. A total of 57,814 current sheets have been identified, among which 25,018 current sheets are located in the slow wind and 19,842 current sheets are located in the fast wind. Significant plasma heating is found at current sheets in both slow and fast wind. Proton temperature increases more significantly at current sheets in the fast wind than in the slow wind, while the enhancement in electron temperature is less remarkable at current sheets in the fast wind. The results reveal that plasma heating commonly exists at thin current sheets in the solar wind regardless of the wind speed, but the underlying heating mechanisms might be different.

In situ magnetic field measurements during AMPTE solar wind Li+releases

1986 ◽  
Vol 91 (A2) ◽  
pp. 1261 ◽  
Author(s):  
H. Lühr ◽  
D. J. Southwood ◽  
N. Klöcker ◽  
M. Acuña ◽  
B. Häusler ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Measurements ◽  
Magnetic Field Measurements

scholarly journals How much solar wind data are sufficient for accurate fluxgate magnetometer offset determinations?

2019 ◽  
Author(s):  
Ferdinand Plaschke
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Measurements ◽  
Wind Data ◽  
Fluxgate Magnetometer ◽  
Time Intervals ◽  
Sensor Position ◽  
Magnetic Field Measurements ◽  
Wind Measurements ◽  
The Magnetic Field

Abstract. Accurate magnetic field measurements by fluxgate magnetometers on-board spacecraft require ground and regular in-flight calibrations activities. Therewith, the parameters of a coupling matrix and an offset vector are adjusted; they are needed to transform raw magnetometer outputs into calibrated magnetic field measurements. The components of the offset vector are typically determined by analyzing Alfvénic fluctuations in the solar wind, if solar wind measurements are available. These are characterized by changes in the field components, while the magnetic field modulus stays constant. In this paper, the following question is answered: How much solar wind data are sufficient for accurate fluxgate magnetometer offset determinations? It is found that approximately 50 hours of solar wind data are sufficient to achieve offset accuracies of 0.2 nT, and about 20 hours suffice for accuracies of 0.3 nT or better, if the magnetometer offsets do not drift within these time intervals and if the spacecraft fields do not vary at the sensor position. Offset determinations with uncertainties lower than 0.1 nT, however, would require at least hundreds of hours of solar wind data.

scholarly journals Spin axis offset calibration on THEMIS using mirror modes

2017 ◽  
Vol 35 (1) ◽  
pp. 117-121 ◽  
Author(s):  
Dennis Frühauff ◽  
Ferdinand Plaschke ◽  
Karl-Heinz Glassmeier
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Observation ◽  
Field Measurements ◽  
Substantial Improvement ◽  
Spin Axis ◽  
Determination Method ◽  
Magnetic Field Measurements ◽  
Axis Offset

Abstract. A newly developed method for determining spin axis offsets of magnetic field instruments on spacecraft is applied to THEMIS. The formerly used determination method, relying on solar wind Alfvénic fluctuations, was rarely applicable due to the orbital restrictions of the mission. With the new procedure, based on magnetic field observation of mirror modes in the magnetosheath, updated spin axis offsets can be estimated approximately once per year. Retrospective calibration of all THEMIS magnetic field measurements is thereby made possible. Since, up to this point, spin axis offsets could hardly ever be calculated due to the mission's orbits, this update represents a substantial improvement to the data. The approximate offset stability is estimated to be < 0.75 nT year−1 for the complete course of the mission.

scholarly journals Estimating the solar wind pressure at comet 67P from Rosetta magnetic field measurements

2019 ◽  
Vol 9 ◽  
pp. A3 ◽  
Author(s):  
Aniko Timar ◽  
Zoltan Nemeth ◽  
Karoly Szego ◽  
Melinda Dósa ◽  
Andrea Opitz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Space Weather ◽  
Field Measurements ◽  
Wind Pressure ◽  
Time Interval ◽  
Pile Up ◽  
Magnetic Field Measurements ◽  
Solar Wind Pressure ◽  
Comet 67P

Aims: The solar wind pressure is an important parameter of space weather, which plays a crucial role in the interaction of the solar wind with the planetary plasma environment. Here we investigate the possibility of determining a solar wind pressure proxy from Rosetta magnetic field data, measured deep inside the induced magnetosphere of comet 67P/Churyumov-Gerasimenko. This pressure proxy would be useful not only for other Rosetta related studies but could also serve as a new, independent input database for space weather propagation to other locations in the Solar System. Method: For the induced magnetospheres of comets the magnetic pressure in the innermost part of the pile-up region is balanced by the solar wind dynamic pressure. Recent investigations of Rosetta data have revealed that the maximum magnetic field in the pile-up region can be approximated by magnetic field measurements performed in the inner regions of the cometary magnetosphere, close to the boundary of the diamagnetic cavity, from which the external solar wind pressure can be estimated. Results: We were able to determine a solar wind pressure proxy for the time interval when the Rosetta spacecraft was located near the diamagnetic cavity boundary, between late April 2015 and January 2016. We then compared our Rosetta pressure proxy to solar wind pressure extrapolated to comet 67P from near-Earth. After the exclusion of disturbances caused by transient events, we found a strong correlation between the two datasets.

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