Engineering topics

Baker, Daniel

Publications and source records attributed to Baker, Daniel.

3 records

NASA NTRS2019

Recent Advances in Our Understanding of the Earth's Radiation Belts

The Earth's radiation belts were discovered by James van Allen more than fifty years ago and are a home to a plethora of fascinating processes ranging from low energy cold plasma to relativistic and ultra-relativistic particle populations. The traditional morphological picture of the radiation belts is that of an outer belt comprising mostly of electrons and an inner belt comprising mostly of protons with a so-called slot region separating the two. The inner belt is somewhat stable, while the outer radiation belt is very dynamical and shows variability in energetic electron populations over a wide range of energies, intensities, and time scales ranging from minutes, days and even years. This variability is due to dynamical processes of energization and loss with a variety of plasma waves playing an important and crucial role. The traditional picture has recently been challenged with new observations coming from the twin spacecraft mission, Van Allen Probes launched in the fall of 2012, which carries a comprehensive suite of instruments that measure particles and plasma waves. In more than 5 years of observations Van Allen Probes has advanced our understanding of fundamental questions regarding the acceleration and loss of outer Van Allen belt electron population. Van Allen Probes observations have also revealed new phenomena such as the "electron Storage ring", and the "impenetrable barrier". This article reviews electron dynamics in the Van Allen belts focusing on van Allen Probes observations and discuss exciting new ways of advancing radiation belt science with CubeSats and CubeSat constellations.

Relativistic electrons↗

NASA NTRS2006

Modeling the Self-organized Critical Behavior of the Plasma Sheet Reconnection Dynamics

Analyses of Polar UVI auroral image data reviewed in our other presentation at this meeting (V. Uritsky, A. Klimas) show that bright night-side high-latitude UV emissions exhibit so many of the key properties of systems in self-organized criticality (SOC) that an alternate interpretation has become virtually impossible. It is now necessary to find and model the source of this behavior. We note that the most common models of self-organized criticality are numerical sandpiles. These are, at root, models that govern the transport of some quantity from a region where it is loaded to another where it is unloaded. Transport is enabled by the excitation of a local threshold instability; it is intermittent and bursty, and it exhibits a number of scale-free statistical properties. Searching for a system in the magnetosphere that is analogous and that, in addition, is known to produce auroral signatures, we focus on the reconnection dynamics of the plasma sheet. In our previous work, a driven reconnection model has been constructed and has been under study. The transport of electromagnetic (primarily magnetic) energy carried by the Poynting flux into the reconnection region of the model has been examined. All of the analysis techniques, and more, that have been applied to the auroral image data have also been applied to this Poynting flux. Here, we report new results showing that this model also exhibits so many of the key properties of systems in self-organized criticality that an alternate interpretation is implausible. Further, we find a strong correlation between these key properties of the model and those of the auroral UV emissions. We suggest that, in general, the driven reconnection model is an important step toward a realistic plasma physical model of self-organized criticality and we conclude, more specifically, that it is also a step in the right direction toward modeling the multiscale reconnection dynamics of the magnetotail.

Klimas, Alex↗

NASA NTRS1985

An implementation plan for priorities in solar-system space physics

The scientific objectives and implementation plans and priorities of the Space Science Board in areas of solar physics, heliospheric physics, magnetospheric physics, upper atmosphere physics, solar-terrestrial coupling, and comparative planetary studies are discussed and recommended programs are summarized. Accomplishments of Skylab, Solar Maximum Mission, Nimbus-7, and 11 other programs are highlighted. Detailed mission plans in areas of solar and heliospheric physics, plasma physics, and upper atmospheric physics are also described.

Krimigis, Stamatios M.↗