How likely is a space weather‐induced U.S. power grid catastrophe? JASON weighs in

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96270/1/swe548.pd

Connecting the Sun to the heliosphere

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95493/1/eost15805.pd

The debate on protons and electrons in solar flares

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95153/1/eost11401.pd

Picture of outer heliosphere develops with new data

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95349/1/eost13968.pd

Implications of the observed anticorrelation between solar wind speed and coronal electron temperature

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95059/1/jgra16514.pd

Active‐Region Sources of Solar Wind near Solar Maximum

Previous studies of the source regions of solar wind sampled by ACE and Ulysses showed that some solar wind originates from open flux areas in active regions. These sources were labeled active region sources when there was no corresponding coronal hole in the He 10830 Å synoptic maps. Here, we present results on an investigation of the magnetic topology of these active region sources and a search for corresponding features in EUV and soft X‐ray images. In most, but not all, cases, a dark hole or lane is seen in the EUV and SXT image as for familiar coronal hole sources. However, in one case, the soft‐X ray images and the magnetic model showed a coronal structure quite different from typical coronal hole structure. Using ACE data, we also find that the solar wind from these active region sources generally has a higher Oxygen charge state than wind from the Helium‐10830Å coronal hole sources, indicating a hotter source region, consistent with the active region source interpretation. © 2003 American Institute of PhysicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87649/2/51_1.pd

Top hat electrostatic analyzer for far-field electric propulsion plume diagnostics

The design, development, and testing of the top hat electric propulsion plume analyzer (TOPAZ) are presented for far-field electric propulsion plume diagnostics. The trend towards high-power thruster development will require plume diagnostic techniques capable of measuring high-energy particles as well as low-energy ions produced from charge-exchange collisions due to elevated facility background pressures. TOPAZ incorporates a “top hat” design with a geometrical analyzer constant of 100 resulting in a wide energy range and a high-energy resolution. SIMION, an ion trajectory analysis program, was used to predict characteristics of the analyzer. An ion beam accelerator system confirms the computational results. TOPAZ provides an energy resolution of 2.7%, field of view of 112°×26°112°×26° (azimuthal by elevation) with an angular resolution in each direction of 2°, and a demonstrated energy-per-charge acceptance range of 5–15 keV5–15keV. An energy profile measurement of the NASA-173Mv1 Hall thruster demonstrates instrument operation in a Hall thruster plume.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87897/2/013505_1.pd

A Brief History of CME Science

We present here a brief summary of the rich heritage of observational and theoretical research leading to the development of our current understanding of the initiation, structure, and evolution of Coronal Mass Ejections

Understanding the Solar Sources of In Situ Observations

The solar wind can, to a good approximation be described as a two‐component flow with fast, tenuous, quiescent flow emanating from coronal holes, and slow, dense and variable flow associated with the boundary between open and closed magnetic fields. In spite of its simplicity, this picture naturally produces a range of complex heliospheric phenomena, including the presence, location, and orientation of corotating interaction regions and their associated shocks. In this study, we apply a two‐step mapping technique, incorporating a magnetohydrodynamic model of the solar corona, to bring in situ observations from Ulysses, WIND, and ACE back to the solar surface in an effort to determine some intrinsic properties of the quasi‐steady solar wind. In particular, we find that a “layer” of ∼35,000 km exists between the Coronal Hole Boundary (CHB) and the fast solar wind, where the wind is slow and variable. We also derive a velocity gradient within large polar coronal holes (that were present during Ulysses’ rapid latitude scan) as a function of distance from the CHB. We find that v = 713 km/s + 3.2 d, where d is the angular distance from the CHB boundary in degrees. © 2003 American Institute of PhysicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87654/2/79_1.pd