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V Angelopoulos - One of the best experts on this subject based on the ideXlab platform.
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in situ evidence of electron Energization in the electron diffusion region of magnetotail reconnection
Journal of Geophysical Research, 2016Co-Authors: Tai Phan, M Oieroset, V AngelopoulosAbstract:Magnetic reconnection is an explosive energy-release process in laboratory, space, and astrophysical plasmas. While magnetic fields can “break” and “reconnect” in a very small region called the electron diffusion region (EDR), there have been conflicting theories as to whether this region can be a place of rapid Energization of plasmas. Here we report a fortuitous encounter of the EDR by The Time History of Events and Macroscale Interactions during Substorms (THEMIS) in the Earth's magnetotail where significant heating and demagnetization of electrons were observed. Additional Energization was observed on both sides (immediate upstream and downstream) of the EDR, leading to a total of more than an order of magnitude Energization across this region. The results demonstrate that despite its minuscule size, the EDR does indeed contribute to the overall process of electron Energization via magnetic reconnection.
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in situ evidence of electron Energization in the electron diffusion region of magnetotail reconnection
Journal of Geophysical Research, 2016Co-Authors: M Oka, M Oieroset, T D Phan, V AngelopoulosAbstract:Magnetic reconnection is an explosive energy-release process in laboratory, space, and astrophysical plasmas. While magnetic fields can “break” and “reconnect” in a very small region called the electron diffusion region (EDR), there have been conflicting theories as to whether this region can be a place of rapid Energization of plasmas. Here we report a fortuitous encounter of the EDR by The Time History of Events and Macroscale Interactions during Substorms (THEMIS) in the Earth's magnetotail where significant heating and demagnetization of electrons were observed. Additional Energization was observed on both sides (immediate upstream and downstream) of the EDR, leading to a total of more than an order of magnitude Energization across this region. The results demonstrate that despite its minuscule size, the EDR does indeed contribute to the overall process of electron Energization via magnetic reconnection.
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in situ evidence of electron Energization in the electron diffusion region of magnetotail reconnection
arXiv: Space Physics, 2016Co-Authors: M Oka, M Oieroset, T D Phan, V AngelopoulosAbstract:Magnetic reconnection is an explosive energy-release process in laboratory, space and astrophysical plasmas. While magnetic fields can `break' and `reconnect' in a very small region called the electron diffusion region (EDR), there have been conflicting theories as to whether this region can be a place of rapid Energization of plasmas. Here we report a fortuitous encounter of the EDR by THEMIS in the Earth's magnetotail where significant heating and demagnetization of electrons were observed. Additional Energization was observed on both sides (immediate upstream and downstream) of the EDR, leading to a total of more than an order of magnitude Energization across this region. The results demonstrate that, despite its minuscule size, the EDR does indeed contribute to the overall process of electron Energization via magnetic reconnection.
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in situ evidence of electron Energization in the electron diffusion region of magnetotail reconnection
arXiv: Space Physics, 2016Co-Authors: Tai Phan, M Oieroset, V AngelopoulosAbstract:Magnetic reconnection is an explosive energy-release process in laboratory, space and astrophysical plasmas. While magnetic fields can `break' and `reconnect' in a very small region called the electron diffusion region (EDR), there have been conflicting theories as to whether this region can be a place of rapid Energization of plasmas. Here we report a fortuitous encounter of the EDR by THEMIS in the Earth's magnetotail where significant heating and demagnetization of electrons were observed. Additional Energization was observed on both sides (immediate upstream and downstream) of the EDR, leading to a total of more than an order of magnitude Energization across this region. The results demonstrate that, despite its minuscule size, the EDR does indeed contribute to the overall process of electron Energization via magnetic reconnection.
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direct evidence for a three dimensional magnetic flux rope flanked by two active magnetic reconnection x lines at earth s magnetopause
Physical Review Letters, 2011Co-Authors: M Oieroset, T D Phan, J P Eastwood, M Fujimoto, W Daughton, M A Shay, V Angelopoulos, F S Mozer, J P Mcfadden, D E LarsonAbstract:: We report the direct detection by three THEMIS spacecraft of a magnetic flux rope flanked by two active X lines producing colliding plasma jets near the center of the flux rope. The observed density depletion and open magnetic field topology inside the flux rope reveal important three-dimensional effects. There was also evidence for nonthermal electron Energization within the flux rope core where the fluxes of 1-4 keV superthermal electrons were higher than those in the converging reconnection jets. The observed ion and electron Energizations differ from current theoretical predictions.
M Oieroset - One of the best experts on this subject based on the ideXlab platform.
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in situ evidence of electron Energization in the electron diffusion region of magnetotail reconnection
Journal of Geophysical Research, 2016Co-Authors: Tai Phan, M Oieroset, V AngelopoulosAbstract:Magnetic reconnection is an explosive energy-release process in laboratory, space, and astrophysical plasmas. While magnetic fields can “break” and “reconnect” in a very small region called the electron diffusion region (EDR), there have been conflicting theories as to whether this region can be a place of rapid Energization of plasmas. Here we report a fortuitous encounter of the EDR by The Time History of Events and Macroscale Interactions during Substorms (THEMIS) in the Earth's magnetotail where significant heating and demagnetization of electrons were observed. Additional Energization was observed on both sides (immediate upstream and downstream) of the EDR, leading to a total of more than an order of magnitude Energization across this region. The results demonstrate that despite its minuscule size, the EDR does indeed contribute to the overall process of electron Energization via magnetic reconnection.
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in situ evidence of electron Energization in the electron diffusion region of magnetotail reconnection
Journal of Geophysical Research, 2016Co-Authors: M Oka, M Oieroset, T D Phan, V AngelopoulosAbstract:Magnetic reconnection is an explosive energy-release process in laboratory, space, and astrophysical plasmas. While magnetic fields can “break” and “reconnect” in a very small region called the electron diffusion region (EDR), there have been conflicting theories as to whether this region can be a place of rapid Energization of plasmas. Here we report a fortuitous encounter of the EDR by The Time History of Events and Macroscale Interactions during Substorms (THEMIS) in the Earth's magnetotail where significant heating and demagnetization of electrons were observed. Additional Energization was observed on both sides (immediate upstream and downstream) of the EDR, leading to a total of more than an order of magnitude Energization across this region. The results demonstrate that despite its minuscule size, the EDR does indeed contribute to the overall process of electron Energization via magnetic reconnection.
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in situ evidence of electron Energization in the electron diffusion region of magnetotail reconnection
arXiv: Space Physics, 2016Co-Authors: M Oka, M Oieroset, T D Phan, V AngelopoulosAbstract:Magnetic reconnection is an explosive energy-release process in laboratory, space and astrophysical plasmas. While magnetic fields can `break' and `reconnect' in a very small region called the electron diffusion region (EDR), there have been conflicting theories as to whether this region can be a place of rapid Energization of plasmas. Here we report a fortuitous encounter of the EDR by THEMIS in the Earth's magnetotail where significant heating and demagnetization of electrons were observed. Additional Energization was observed on both sides (immediate upstream and downstream) of the EDR, leading to a total of more than an order of magnitude Energization across this region. The results demonstrate that, despite its minuscule size, the EDR does indeed contribute to the overall process of electron Energization via magnetic reconnection.
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in situ evidence of electron Energization in the electron diffusion region of magnetotail reconnection
arXiv: Space Physics, 2016Co-Authors: Tai Phan, M Oieroset, V AngelopoulosAbstract:Magnetic reconnection is an explosive energy-release process in laboratory, space and astrophysical plasmas. While magnetic fields can `break' and `reconnect' in a very small region called the electron diffusion region (EDR), there have been conflicting theories as to whether this region can be a place of rapid Energization of plasmas. Here we report a fortuitous encounter of the EDR by THEMIS in the Earth's magnetotail where significant heating and demagnetization of electrons were observed. Additional Energization was observed on both sides (immediate upstream and downstream) of the EDR, leading to a total of more than an order of magnitude Energization across this region. The results demonstrate that, despite its minuscule size, the EDR does indeed contribute to the overall process of electron Energization via magnetic reconnection.
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direct evidence for a three dimensional magnetic flux rope flanked by two active magnetic reconnection x lines at earth s magnetopause
Physical Review Letters, 2011Co-Authors: M Oieroset, T D Phan, J P Eastwood, M Fujimoto, W Daughton, M A Shay, V Angelopoulos, F S Mozer, J P Mcfadden, D E LarsonAbstract:: We report the direct detection by three THEMIS spacecraft of a magnetic flux rope flanked by two active X lines producing colliding plasma jets near the center of the flux rope. The observed density depletion and open magnetic field topology inside the flux rope reveal important three-dimensional effects. There was also evidence for nonthermal electron Energization within the flux rope core where the fluxes of 1-4 keV superthermal electrons were higher than those in the converging reconnection jets. The observed ion and electron Energizations differ from current theoretical predictions.
Dominique Delcourt - One of the best experts on this subject based on the ideXlab platform.
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Sodium Ion Dynamics in the Magnetospheric Flanks of Mercury
Geophysical Research Letters, 2018Co-Authors: Sae Aizawa, Dominique Delcourt, N. TeradaAbstract:We investigate the transport of planetary ions in the magnetospheric flanks of Mercury. In situ measurements from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft show evidences of Kelvin-Helmholtz instability development in this region of space, due to the velocity shear between the downtail streaming flow of solar wind originating protons in the magnetosheath and the magnetospheric populations. Ions that originate from the planet exosphere and that gain access to this region of space may be transported across the magnetopause along meandering orbits. We examine this transport using single-particle trajectory calculations in model Magnetohydrodynamics simulations of the Kelvin-Helmholtz instability. We show that heavy ions of planetary origin such as Na may experience prominent nonadiabatic Energization as they E × B drift across large-scale rolled up vortices. This Energization is controlled by the characteristics of the electric field burst encountered along the particle path, the net energy change realized corresponding to the maximum E × B drift energy. This nonadiabatic Energization also is responsible for prominent scattering of the particles toward the direction perpendicular to the magnetic field.
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Protons and heavy ions acceleration by electromagnetic fluctuations in the Earth's magnetotail
2017Co-Authors: F. Catapano, Dominique Delcourt, G. Zimbardo, S. Perri, A. Greco, Alessandro RetinòAbstract:Energetic protons and heavy ions are very often observed in the Earth's magnetotail, as shown by numerous spacecraft observations. Yet the acceleration mechanism causing such Energization is still under debate. One important candidate is the acceleration by electromagnetic fields fluctuations, which are also very often observed in the magnetotail. Here we perform test particle simulations in which protons and heavier ions are injected in three-dimensional time-dependent stochastic electromagnetic perturbations superposed to an unperturbed magnetic field configuration. We study the Energization process for H , He and O ions by performing a detailed analysis of particle dynamics. We find that light ions are preferentially energized and that the level of fluctuations affects the Energization rate. We also compare the results from the model with MMS spacecraft observations.
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Mercury's Plasma Mantle during Solar Wind Dynamical Pressure Enhancements
2014Co-Authors: Dominique Delcourt, Kanako Seki, Naoki Terada, T. E. MooreAbstract:Because of the weak planetary magnetic field as well as proximity to the Sun, the magnetosphere of Mercury is very dynamical and at times subjected to prominent compression. Recent observations from MESSENGER reveal that during events of enhanced solar wind dynamical pressure, the subsolar magnetopause may actually be pushed until the immediate vicinity of the planet surface. Using three-dimensional single-particle simulations, we examine the dynamics of solar wind originating protons during such events. We show that these impulsive events can lead to substantial (several hundreds of eVs or a few keVs) H Energization in the plasma mantle. Unlike ions with large mass-to-charge ratios (e.g., Na of planetary origin), H are transported adiabatically during these events, their Energization being due to the ExB convection surge. MESSENGER observations of the plasma mantle show repeated evidences of such a transient H Energization which may follow from the variable character of Mercury's magnetosphere.
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Ion dynamics during compression of Mercury's magnetosphere
Annales Geophysicae, 2010Co-Authors: Dominique Delcourt, T. E. Moore, M.-c. FokAbstract:Because of the small planetary magnetic field as well as proximity to the Sun that leads to enhanced solar wind pressure as compared to Earth, the magnetosphere of Mercury is very dynamical and at times subjected to prominent compression. We investigate the dynamics of magnetospheric ions during such compression events. Using three-dimensional single-particle simulations, we show that the electric field induced by the time varying magnetic field can lead to significant ion Energization, up to several hundreds of eVs or a few keVs. This Energization occurs in a nonadiabatic manner, being characterized by large enhancements of the ion magnetic moment and bunching in gyration phase. It is obtained when the ion cyclotron period is comparable to the field variation time scale. This condition for nonadiabatic heating is realized in distinct regions of space for ions with different mass-to-charge ratios. During compression of Mercury's magnetosphere, heavy ions originating from the planetary exosphere may be subjected to such an abrupt Energization, leading to loading of the magnetospheric lobes with energetic material.
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Ion Energization during substorms at Mercury
Planetary and Space Science, 2007Co-Authors: Dominique Delcourt, François Leblanc, Kanako Seki, Naoki Terada, T. E. Moore, M.-c. FokAbstract:We investigate the dynamics of magnetospheric ions during transient reconfigurations of Mercury's magnetotail. At Earth, numerous observations during similar events reveal a prominent Energization (up to the hundreds of keV range) of heavy ions (O+) originating from the topside ionosphere. This Energization likely results from a resonant nonadiabatic interaction with the electric field that is induced by dipolarization of the magnetic field lines, the time scale of this reconfiguration being comparable to the heavy ion cyclotron period. The question then arises whether such an Energization may occur at Mercury. Using single-particle simulations in time-varying electric and magnetic fields, we show that prominent nonadiabatic heating is obtained for ions with small mass-to-charge ratios (e.g., Click to view the MathML source). As for heavy ions (e.g., Click to view the MathML source) that have cyclotron periods well above the time scale of the magnetotail reconfiguration (several seconds), a weaker Energization is obtained. The resonant heating mechanism that we examine here may be of importance for solar wind protons that gain access to the inner hermean magnetotail as well as for light ions of planetary origin that directly feed the near-Mercury plasma sheet.
Gabriele Oettingen - One of the best experts on this subject based on the ideXlab platform.
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Future Thought and the Self-Regulation of Energization
Handbook of Biobehavioral Approaches to Self-Regulation, 2014Co-Authors: A. Timur Sevincer, Gabriele OettingenAbstract:The chapter explores how different forms of thinking about the future affect the self-regulation of energy mobilization for goal pursuit as assessed by its physiological underpinnings (i.e., cardiovascular response). Counter to what the popular self-help literature proposes, positive thinking can be detrimental to energy mobilization (i.e., Energization) if it comes in the form of fantasies (free thoughts and images about the desired future) rather than beliefs (expectations). Indeed, fantasizing positively about a desired future leads to a decreased Energization as indicated by a dampened cardiovascular response. Fantasy realization theory, however, specifies how positive fantasies can be used to wisely self-regulate Energization for goal pursuit. According to the theory, the strategy of mental contrasting future and reality will increase or decrease Energization, depending on a person’s high versus low expectations of success, respectively. Indeed, mental contrasting leads to an increased or decreased Energization (measured by cardiovascular response and self-report) depending on expectations of success. The increased or decreased cardiovascular response in turn predicted performance in goal pursuit. Moreover, drawing on Hull’s conception of Energization as an unspecific activation state, a recent series of studies found that Energization triggered by mental contrasting in one domain may carry-over to another domain to fuel goal striving behavior with regard to an unrelated task. We discuss the relation of the findings to other models of physiological self-regulation, such as Brehm’s theory of motivation, the biopsychosocial model of arousal regulation, and excitation transfer theory. Finally, implications for interventions geared at improving self-regulation of effort are discussed.
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Mental Contrasting and Transfer of Energization
Personality and Social Psychology Bulletin, 2014Co-Authors: A. Timur Sevincer, P. Daniel Busatta, Gabriele OettingenAbstract:Mental contrasting a desired future with present reality is a self-regulation strategy that fosters Energization in line with a person's expectations of successfully attaining the desired future. We investigated whether physiological Energization (measured by systolic blood pressure) elicited by mental contrasting a desired future of solving a given task transfers to effort in an unrelated task. As predicted, mental contrasting a desired future of excelling in an intelligence test (Study 1) and of writing an excellent essay (Study 2) triggered changes in Energization that translated into physical effort in squeezing a handgrip (Study 1) and translated into mental effort in writing a get-well letter (Study 2). Results suggest that mental contrasting of solving one task triggers Energization that may fuel effort for performing an unrelated task. Implications for intervention research are discussed.
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Mental Contrasting and Goal Commitment: The Mediating Role of Energization
Personality & social psychology bulletin, 2009Co-Authors: Gabriele Oettingen, A. Timur Sevincer, Doris Mayer, Elizabeth J. Stephens, Hyeon Ju Pak, Meike HagenahAbstract:Mentally contrasting a desired future with present reality is a self-regulation strategy that leads to goal commitment in line with a person's expectations of success. One possible mediator variable of these effects is level of Energization. In Study 1, Energization assessed by physiological measures was found to mediate the effect of mental contrasting on goal commitment. In Study 2, feelings of Energization, as assessed by self-report, mediated the effect of mental contrasting on goal commitment as gauged by performance on an acute stress paradigm (giving a talk in front of a camera). Results imply that when expectations of success are high, mental contrasting provides the level of energy needed to commit to realizing desired futures.
Urmil Parikh - One of the best experts on this subject based on the ideXlab platform.
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controlled switching of unloaded power transformer colcabamba case with 500 230 33 kv auto transfomer
IEEE PES Transmission and Distribution Conference and Exhibition, 2018Co-Authors: D. F. Rodríguez, Urmil Parikh, Michael StanekAbstract:This paper presents the application of a controlled switching system for energizing a 500/230/33 kV auto transformer with delta connected tertiary winding in Colcabamba substation, Peru. Controlled switching is used to reduce grid voltage drop during no load Energization of power transformer due to high inrush current during its charging; specifically, controlled deEnergization to lock residual flux at lowest possible level followed by controlled Energization considering residual flux to achieve inrush current mitigation. A verified simple and easily applicable approach to estimate residual flux in individual phases based on inrush peaks obtained during first time Energization of power transformers is used to further reduce inrush current to best possible levels.
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Controlled Switching of Unloaded Power transformer- Colcabamba Case with 500/230/33 kV Auto Transfomer
2018 IEEE PES Transmission & Distribution Conference and Exhibition - Latin America (T&D-LA), 2018Co-Authors: D. F. Rodríguez, Urmil Parikh, Michael StanekAbstract:This paper presents the application of a controlled switching system for energizing a 500/230/33 kV auto transformer with delta connected tertiary winding in Colcabamba substation, Peru. Controlled switching is used to reduce grid voltage drop during no load Energization of power transformer due to high inrush current during its charging; specifically, controlled deEnergization to lock residual flux at lowest possible level followed by controlled Energization considering residual flux to achieve inrush current mitigation. A verified simple and easily applicable approach to estimate residual flux in individual phases based on inrush peaks obtained during first time Energization of power transformers is used to further reduce inrush current to best possible levels.
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challenges in field implementation of controlled Energization for various equipment loads with circuit breakers considering diversified dielectric and mechanical characteristics
International Journal of Electrical Power & Energy Systems, 2017Co-Authors: Urmil Parikh, Bhavesh R BhaljaAbstract:Abstract The close coordination between circuit breaker (CB) characteristics and behavior of equipment to be switched plays key role in achieving desired mitigation results during controlled switching. In this respect, usually, controlled closing is found to be more challenging compared to controlled opening. This paper presents key aspects in context to performance assessment of a CB during controlled Energization of various equipment loads based on its mechanical and dielectric characteristics. The Energization target may vary from CB gap voltage zero to peak depending upon the behavior of the equipment to be switched. In this context, the procedure of evaluating Energization targets for various power system loads with diversified design and connection configurations have been elaborated. Furthermore, the way to analyze suitability of CB characteristics for achieving a range of Energization targets having different closing speed and time scatter; especially breakers with slow closing speed have been discussed in detail. The challenges due to operating time scatter and inter phase coupling for transformers and uncompensated transmission lines have been analyzed in conjunction with field results. Finally, comparison of mitigation effects obtained during Energization of shunt reactor with dissimilar CB operating characteristics on an existing 400 kV Indian transmission network has been presented.