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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Global MHD Simulation of Mesoscale Structures at the Magnetospheric Boundary

The research carried out for this protocol was focused on the study of mesoscales structures at the magnetospheric boundary. We investigated three areas: (1) the structure of the magnetospheric boundary for steady solar wind conditions; (2) the dynamics of the dayside magnetospheric boundary and (3) the dynamics of the distant tail magnetospheric boundary. Our approach was to use high resolution three-dimensional global magnetohydrodynamic (MHD) simulations of the interaction of the solar wind with the Earth's magnetosphere. We first considered simple variations of the interplanetary conditions to obtain generic cases that helped us in establishing the basic cause and effect relationships for steady solar wind conditions. Subsequently, we used actual solar wind plasma and magnetic field parameters measured by an upstream spacecraft as input to the simulations and compared the simulation results with sequences of events observed by another or several other spacecraft located downstream the bow shock. In particular we compared results with observations made when spacecraft crossed the magnetospheric boundary.

Berchem, Jean↗
NASA NTRS2013

Ensemble Forecasting of Coronal Mass Ejections Using the WSA-ENLIL with CONED Model

The combination of the Wang-Sheeley-Arge (WSA) coronal model, ENLIL heliospherical model version 2.7, and CONED Model version 1.3 (WSA-ENLIL with CONED Model) was employed to form ensemble forecasts for 15 halo coronal mass ejections (halo CMEs). The input parameter distributions were formed from 100 sets of CME cone parameters derived from the CONED Model. The CONED Model used image processing along with the bootstrap approach to automatically calculate cone parameter distributions from SOHO/LASCO imagery based on techniques described by Pulkkinen et al. (2010). The input parameter distributions were used as input to WSA-ENLIL to calculate the temporal evolution of the CMEs, which were analyzed to determine the propagation times to the L1 Lagrangian point and the maximum Kp indices due to the impact of the CMEs on the Earth's magnetosphere. The Newell et al. (2007) Kp index formula was employed to calculate the maximum Kp indices based on the predicted solar wind parameters near Earth assuming two magnetic field orientations: a completely southward magnetic field and a uniformly distributed clock-angle in the Newell et al. (2007) Kp index formula. The forecasts for 5 of the 15 events had accuracy such that the actual propagation time was within the ensemble average plus or minus one standard deviation. Using the completely southward magnetic field assumption, 10 of the 15 events contained the actual maximum Kp index within the range of the ensemble forecast, compared to 9 of the 15 events when using a uniformly distributed clock angle.

coronal mass↗
NASA NTRS1997

Magnetospheric Plasmas-Flow and Energization of the Ionospheric Source

In a paper of more than a decade ago, estimated the strength of the ionospheric source and its ability to supply the different plasma regions of the Earth's magnetosphere. The launch of the POLAR spacecraft with the Thermal Ion Dynamics Experiment (TIDE) and the active control of spacecraft potential thro6gh the Plasma Source Instrument (PSI) made possible for the first time the direct measurement of low energy ions moving from the ionosphere into the lobes of the magnetotail. A particle trajectory model has been used to trace particles representative 6f TIDE measurements, taken during the operation of PSI, back to the location of the ionospheric source and forward to the entry point of the ions to the plasma sheet.

Chappell, C. R.↗
NASA NTRS1997

Magnetospheric Plasmas: A Direct Measurement of the Ionospheric Source

In a paper of more than a decade ago, the estimated the strength of the ionospheric source and its ability to supply the different plasma regions of the Earth's magnetosphere was reported. The launch of the POLAR spacecraft with the Thermal Ion Dynamics Experiment (TIDE) and the active control of spacecraft potential made possible for the first time the direct measurement of low energy ions moving from the ionosphere into the lobes of the magnetotail. This paper presents data taken during the period of operation of the Plasma Source Instrument (PSI) which maintains the spacecraft potential at about 1.8V positive with respect to the ambient plasma. These data give an in-situ observation of the strength and flow direction of the ionospheric plasmas as it moves outward into the lobes of the tail. A particle trajectory model has been used to trace particles back to the location of the ionospheric source and forward to the entry point of the ions to the plasma sheet. A comparison of measured data with the predictions of the earlier modeling effort will be discussed.

Giles, B. L.↗
NASA NTRS2011

Monte Carlo Simulations of the Formation Flying Dynamics for the Magnetospheric Multiscale (MMS) Mission

The MMS mission is an ambitious space physics mission that will fly 4 spacecraft in a tetrahedron formation in a series of highly elliptical orbits in order to study magnetic reconnection in the Earth's magnetosphere. The mission design is comprised of a combination of deterministic orbit adjust and random maintenance maneuvers distributed over the 2.5 year mission life. Formal verification of the requirements is achieved by analysis through the use of the End-to-End (ETE) code, which is a modular simulation of the maneuver operations over the entire mission duration. Error models for navigation accuracy (knowledge) and maneuver execution (control) are incorporated to realistically simulate the possible maneuver scenarios that might be realized These error models, coupled with the complex formation flying physics, lead to non-trivial effects that must be taken into account by the ETE automation. Using the ETE code, the MMS Flight Dynamics team was able to demonstrate that the current mission design satisfies the mission requirements.

Schiff, Conrad↗
NASA NTRS1992

Nonlinear dynamics of charged particles in the magnetotail

An important region of the earth's magnetosphere is the nightside magnetotail, which is believed to play a significant role in energy storage and release associated with substorms. The magnetotail contains a current sheet which separates regions of oppositely directed magnetic field. Particle motion in the collisionless magnetotail has been a long-standing problem. Recent research from the dynamical point of view has yielded considerable new insights into the fundamental properties of orbits and of particle distribution functions. A new framework of understanding magnetospheric plasma properties is emerging. Some novel predictions based directly on nonlinear dynamics have proved to be robust and in apparent good agreement with observation. The earth's magnetotail may serve as a paradigm, one accessible by in situ observation, of a broad class of boundary regions with embedded current sheets. This article reviews the nonlinear dynamics of charged particles in the magnetotail configuration. The emphasis is on the relationships between the dynamics and physical observables. At the end of the introduction, sections containing basic material are indicated.

Chen, James↗
NASA NTRS2011

A Globally Stable Lyapunov Pointing and Rate Controller for the Magnetospheric MultiScale Mission (MMS)

The Magnetospheric MultiScale Mission (MMS) is scheduled to launch in late 2014. Its primary goal is to discover the fundamental plasma physics processes of reconnection in the Earth's magnetosphere. Each of the four MMS spacecraft is spin-stabilized at a nominal rate of 3 RPM. Traditional spin-stabilized spacecraft have used a number of separate modes to control nutation, spin rate, and precession. To reduce the number of modes and simplify operations, the Delta-H control mode is designed to accomplish nutation control, spin rate control, and precession control simultaneously. A nonlinear design technique, Lyapunov's method, is used to design the Delta-H control mode. A global spin rate controller selected as the baseline controller for MMS, proved to be insufficient due to an ambiguity in the attitude. Lyapunov's design method was used to solve this ambiguity, resulting in a controller that meets the design goals. Simulation results show the advantage of the pointing and rate controller for maneuvers larger than 90 deg and provide insight into the performance of this controller.

Shah, Neerav↗
NASA NTRS1994

Wind Prelaunch Mission Operations Report (MOR)

The National Aeronautics and Space Administration (NASA) Wind mission is the first mission of the Global Geospace Science (GGS) initiative. The Wind laboratory will study the properties of particles and waves in the region between the Earth and the Sun. Using the Moon s gravity to save fuel, dual lunar swing-by orbits enable the spacecraft to sample regions close to and far from the Earth. During the three year mission, Wind will pass through the bow shock of Earth's magnetosphere to begin a thorough investigation of the solar wind. Mission objectives require spacecraft measurements in two orbits: lunar swing- by ellipses out to distances of 250 Earth radii (RE) and a small orbit around the Lagrangian point L-l that remains between the Earth and the Sun. Wind will be placed into an initial orbit for approximately 2 years. It will then be maneuvered into a transition orbit and ultimately into a halo orbit at the Earth-Sun L-l point where it will operate for the remainder of its lifetime. The Wind satellite development was managed by NASA's Goddard Space Flight Center with the Martin Marietta Corporation, Astro-Space Division serving as the prime contractor. Overall programmatic direction was provided by NASA Headquarters, Office of Space Science. The spacecraft will be launched under a launch service contract with the McDonnell Douglas Corporation on a Delta II Expendable Launch Vehicle (ELV) within a November l-l4, 1994 launch window. The Wind spacecraft carries six U.S. instruments, one French instrument, and the first Russian instrument ever to fly on an American satellite. The Wind and Polar missions are the two components of the GGS Program. Wind is also the second mission of the International Solar Terrestrial Physics (ISTP) Program. The first ISTP mission, Geotail, is a joint project of the Institute of Space and Astronautical Science of Japan and NASA which launched in 1992. The Wind mission is planned to overlap Geotail by six months and Polar by one year. The Wind and Polar missions, together with the Geotail mission (launched on July 24, 1992) and supporting equatorial measurements, will provide simultaneous data to enable the study of solar wind input to the magnetosphere and key elements of the magnetospheric response: ring current energy storage, geomagnetic tail energy storage, and ionospheric energy input.

Source record↗
NASA NTRS1973

Time variations of magnetospheric intensities of outer zone protons, alpha particles and ions (Z greater than or equal to 2)

A comprehensive study of the temporal behavior of trapped protons, alpha particles and ions (Z 2) in outer zone of the earth's magnetosphere has been made. These observations were made by the Injun V satellite during the first 21 months of operation, August 1968 to May 1970. Rapid increases in the observed number of particles followed by slower exponential decay characterize the data. Comparisons are made with the temporal behavior of interplanetary particles of the same energy observed by Explorer 35. Increases in the trapped fluxes generally correspond to enhanced interplanetary activity. The energy spectra of protons and alpha particles at L = 3 have similar shapes when compared on an energy per charge basis while the respective polar cap spectra have similar shape on an energy per nucleon basis. Apparent inward trans-L motion of energetic protons is observed. These particles are diffused inward by a process involving fluctuating electric fields. The loss of trapped low altitude protons, alpha particles and ions (Z 2) is controlled by coulombic energy loss in the atmosphere.

Randall, B. A.↗
DOE OSTI2024

Cold Plasma Measurements

We have continued the simulation campaign in support of our ongoing magnetospheric cold plasma research project. This project aims to develop the next-generation particle instruments to measure the properties of the cold particle populations in the Earth’s magnetosphere. For this purpose, simulations have been performed with a Particle-In-Cell (PIC) code called the Curvilinear PIC (CPIC). The code is formulated in curvilinear geometry and couples the standard PIC algorithm with algorithms for the generation and adaptation of the underlaying computational mesh. It conforms to complex objects like spacecraft and it can place more grid points in regions where higher resolution is needed. The code also features a scalable solver based on the multigrid algorithm and it is fully parallelized via domain decomposition and MPI.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Cold Plasma IC Report

This past year we completed the simulation campaign in support of our magnetospheric cold plasma research project. This project aimed to develop the next-generation particle instruments to measure the properties of the cold particle populations in the Earth’s magnetosphere.

58 GEOSCIENCES↗
NASA NTRS1992

Flank solar wind interaction

This report summarizes the results of the first 12 months of our program to study the interaction of the Earth's magnetosphere with the solar wind on the far flanks of the bow shock. This study employs data from the ISEE-3 spacecraft during its traversals of the Earth's magnetotail and correlative data from spacecraft monitoring the solar wind upstream. Our main effort to date has involved assembling data sets and developing new plotting programs. Two talks were given at the Spring Meeting of the American Geophysical Union describing our initial results from analyzing data from the far flank foreshock and magnetosheath. The following sections summarize our results.

Moses, Stewart L.↗
NASA NTRS1986

The effect of different resistivity models on magnetotail dynamics

Two-dimensional, time-dependent MHD simulations of the interaction between the solar wind and the earth's magnetosphere have been performed to study magnetotail dynamics with varying forms of anomalous resistivity. In general, the resulting models conform to the neutral line model proposed for substorms with near-earth x points and high-speed tailward flows occurring in the magnetotail. However, in the case where Joule heating is included in the physical description of the system, the near-earth x point never moves far down tail, and high-speed tailward flows never stop. Only in the case where there is no Joule heating does the x point move down tail. Simultaneously, the high-speed tailward flows cease. These results indicate that the mechanism of energy dissipation can have an important effect on reconnection processes and the global magnetospheric dynamics.

Lyon, J. G.↗
NASA NTRS1983

Plasma waves in the Jovian magnetosphere

Any waves which are influenced by the presence of a plasma are called plasma waves. In general, plasma waves can be classified as either electromagnetic, which have both electric and magnetic fields, or electrostatic, which have no magnetic field. The recent Voyager encounters provide the basis for the first comprehensive investigation of plasma waves in the magnetosphere of Jupiter. The most striking feature of the Jovian plasma-wave observations is the very close similarity to the plasma-wave phenomena observed in the earth's magnetosphere. In a description of the plasma-wave results obtained with the aid of Voyager, the observed phenomena are discussed in several broad categories. Attention is given to the upstream waves and the bow shock, the trapped continuum radiation, upper hybrid and electron cyclotron waves, whistler-mode waves, and broadband electrostatic noise.

Gurnett, D. A.↗
NASA NTRS2016

Special Issue the 12th International Conference on Substorms

The 12th International Conference on Substorms (ICS-12) was held at the Ise-Shima Royal Hotel in Shima, Japan, on November 10-14, 2014. There were 125 attendees including 68 from foreign countries. The ICS has been held every 2 years since 1992 to discuss substorms, which are fundamental global-scale disturbances in the Earth's magnetosphere. The year 2014 marked the 50th anniversary of the first publication about substorms (Akasofu 1964). The conference included three tutorial lecturers (Profs. S.-I. Akasofu, V. Angelopoulous, and D. Baker), as well as many international scientists, to discuss substorm processes in the tail, their Interactions with the inner magnetosphere and the ionosphere, substorm currents and their dynamics and energetics, the role of MagnetoHydroDynamics (MHD) and kinetic instabilities, storm-substorm relationships, ULFELFVLF waves, and non-Earth substorm-like features. Prof. Akasofu also gave an evening talk about the history of auroral research since the nineteenth century with photographs that inspired and intrigued the young scientists and students in attendance.

Shiokawa, Kazuo↗
NASA NTRS2022

First-Principles Theory of the Rate of Magnetic Reconnection in Magnetospheric and Solar Plasmas

The rate of magnetic reconnection is of the utmost importance in a variety of processes because it controls, for example, the rate energy is released in solar flares, the speed of the Dungey convection cycle in Earth’s magnetosphere, and the energy release rate in harmful geomagnetic substorms. It is known from numerical simulations and satellite observations that the rate is approximately 0.1 in normalized units, but despite years of effort, a full theoretical prediction has not been obtained. Here, we present a first-principles theory for the reconnection rate in non-relativistic electron-ion collisionless plasmas, and show that the same prediction explains why Sweet-Parker reconnection is considerably slower. The key consideration of this analysis is the pressure at the reconnection site (i.e., the x-line). We show that the Hall electromagnetic fields in antiparallel reconnection cause an energy void, equivalently a pressure depletion, at the x-line, so the reconnection exhaust opens out, enabling the fast rate of 0.1. If the energy can reach the x-line to replenish the pressure, the exhaust does not open out. In addition to heliospheric applications, these results are expected to impact reconnection studies in planetary magnetospheres, magnetically confined fusion devices, and astrophysical plasmas.

Yi-Hsin Liu↗
DOE OSTI2015

On the electron dynamics during island coalescence in asymmetric magnetic reconnection

We present an analysis of the electron dynamics during rapid island merging in asymmetric magnetic reconnection. We consider a doubly periodic system with two asymmetric transitions. The upper layer is an asymmetric Harris sheet of finite width perturbed initially to promote a single reconnection site. The lower layer is a tangential discontinuity that promotes the formation of many X-points, separated by rapidly merging islands. Across both layers, the magnetic field and the density have a strong jump, but the pressure is held constant. Our analysis focuses on the consequences of electron energization during island coalescence. We focus first on the parallel and perpendicular components of the electron temperature to establish the presence of possible anisotropies and non-gyrotropies. Thanks to the direct comparison between the two different layers simulated, we can distinguish three main types of behavior characteristic of three different regions of interest. The first type represents the regions where traditional asymmetric reconnections take place without involving island merging. The second type of regions instead shows reconnection events between two merging islands. Finally, the third regions identify the regions between two diverging island and where typical signature of reconnection is not observed. Electrons in these latter regions additionally show a flat-top distribution resulting from the saturation of a two-stream instability generated by the two interacting electron beams from the two nearest reconnection points. Finally, the analysis of agyrotropy shows the presence of a distinct double structure laying all over the lower side facing the higher magnetic field region. This structure becomes quadrupolar in the proximity of the regions of the third type. The distinguishing features found for the three types of regions investigated provide clear indicators to the recently launched Magnetospheric Multiscale NASA mission for investigating magnetopause reconnection involving multiple islands.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

First-principles theory of the rate of magnetic reconnection in magnetospheric and solar plasmas

Abstract The rate of magnetic reconnection is of the utmost importance in a variety of processes because it controls, for example, the rate energy is released in solar flares, the speed of the Dungey convection cycle in Earth’s magnetosphere, and the energy release rate in harmful geomagnetic substorms. It is known from numerical simulations and satellite observations that the rate is approximately 0.1 in normalized units, but despite years of effort, a full theoretical prediction has not been obtained. Here, we present a first-principles theory for the reconnection rate in non-relativistic electron-ion collisionless plasmas, and show that the same prediction explains why Sweet-Parker reconnection is considerably slower. The key consideration of this analysis is the pressure at the reconnection site (i.e., the x-line). We show that the Hall electromagnetic fields in antiparallel reconnection cause an energy void, equivalently a pressure depletion, at the x-line, so the reconnection exhaust opens out, enabling the fast rate of 0.1. If the energy can reach the x-line to replenish the pressure, the exhaust does not open out. In addition to heliospheric applications, these results are expected to impact reconnection studies in planetary magnetospheres, magnetically confined fusion devices, and astrophysical plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗