An e x t e n s i v e s t u d y of t h e dynamic, non-shock p r o p e r t i e s o f t h e m i c r o -s c a l e f l u c t u a t i o n s (scale l e n g t h s of .01 a.u. and 1 e s s ) i n t h e i n t e rp l a n e t a r y medium has been made using plasma and magnetic f i e l d d a t a from Mariner V (Venus 1967). The o b s e r v a t i o n a l r e s u l t s o f t h e s t u d y a r e :(1) l a r g e amplitude, non-sinusoidal Alfv&n waves propagating outward Erom t h e sun w i t h a broad wavelength range from lo3 t o 5 x lo6 km dominate t h e microscale s t r u c t u r e a t l e a s t 50 p e r c e n t o f t h e t i m e ; t h e waves f r e q u e n t l y have energy d e n s i t i e s comparable b o t h t o t h e unperturbed magnetic f i e l d energy d e n s i t y and t o t h e thermal energy d e n s i t y ; of t h e s e outwardly propagating Alfvhn waves occur i n h i g h v e l o c i t y s o l a r wind streams and on t h e i r t r a i l i n g edges (where t h e v e l o c i t y d e c r e a s e s slowly w i t h t i m e ) .propagating, b u t u s u a l l y have s m a l l e r amplitudes t h a n i n t h e f a s t streams, and tend t o be l e s s p u r e i n t h e sense t h a t t h e y a r e more s t r o n g l y intermixed w i t h s t r u c t u r e s o f a non-Alfv6nic and p o s s i b l y s t a t i c n a t u r e ; g e s t amplitude Alfvdnic f l u c t u a t i o n s a r e found i n t h e compression r e g i o n s a t t h e l e a d i n g edges of h i g h v e l o c i t y streams where t h e v e l o c i t y i n c r e a s e s u n i t v e c t o r i n t h e average f i e l d d i r e c t i o n (2) t h e p u r e s t examples I n low v e l o c i t y r e g i o n s Alfv6n waves a r e also outwardly( 3 ) t h e l a rt h e s e r e g i o n s may c o n t a i n s i g n i f i c a n t amounts of inwardly ( 4 ) power s p e c t r a o f t h e i n t e r p l a n et h e s p e c t r a w i t h slower f a l lc o o r d i n a t e system whose axes a r e ( 9 x 3 , 1 and e + is a unit vector radially away from the sun; this anisotropy tends to be strongest (6:3:1) in the compression regions at the leading edges of high velocity streams; (6) presumably magnetoacoustic wave modes occur, but they have not been identified, and, if present, have a small average power of the order of 10 percent or less of that in the Alfven mode.

The solar wind blows outward from the Sun and forms a bubble of solar material in the interstellar medium. The termination shock occurs where the solar wind changes from being supersonic (with respect to the surrounding interstellar medium) to being subsonic. The shock was crossed by Voyager 1 at a heliocentric radius of 94 au (1 au is the Earth-Sun distance) in December 2004 (refs 1-3). The Voyager 2 plasma experiment observed a decrease in solar wind speed commencing on about 9 June 2007, which culminated in several crossings of the termination shock between 30 August and 1 September 2007 (refs 4-7). Since then, Voyager 2 has remained in the heliosheath, the region of shocked solar wind. Here we report observations of plasma at and near the termination shock and in the heliosheath. The heliosphere is asymmetric, pushed inward in the Voyager 2 direction relative to the Voyager 1 direction. The termination shock is a weak, quasi-perpendicular shock that heats the thermal plasma very little. An unexpected finding is that the flow is still supersonic with respect to the thermal ions downstream of the termination shock. Most of the solar wind energy is transferred to the pickup ions or other energetic particles both upstream of and at the termination shock.

The Solar Wind Electrons Alphas and Protons (SWEAP) Investigation on SolarProbe Plus is a four sensor instrument suite that provides complete measurements of the electrons and ionized helium and hydrogen that constitute the bulk of solar wind and coronal plasma. SWEAP consists of the Solar Probe Cup (SPC) and the Solar Probe Analyzers (SPAN). SPC is a Faraday Cup that looks directly at the Sun and measures ion and electron fluxes and flow angles as a function of energy. SPAN consists of an ion and electron electrostatic analyzer (ESA) on the ram side of SPP (SPAN-A) and an electron ESA on the anti-ram side (SPAN-B). The SPAN-A ion ESA has a time of flight section that enables it to sort particles by their mass/charge ratio, permitting differentiation of ion species. SPAN-A and -B are rotated relative to one another so their broad fields of view combine like the seams on a baseball to view the entire sky except for the region obscured by the heat shield and covered by SPC. Observations by SPC and SPAN produce the combined field of view and measurement capabilities required to fulfill the science objectives of SWEAP and Solar Probe Plus. SWEAP measurements, in concert with magnetic and electric fields, energetic particles, and white light contextual imaging will enable discovery and understanding of solar wind acceleration and formation, coronal and solar wind heating, and particle acceleration in the inner heliosphere of the solar system. SPC and SPAN are managed by the SWEAP Electronics Module (SWEM), which distributes power, formats onboard data products, and serves as a single electrical interface to the spacecraft. SWEAP data products include ion and electron velocity distribution functions with high energy and angular resolution. Full resolution data are stored within the SWEM, enabling high resolution observations of structures such as shocks, reconnection events, and other transient structures to be selected for download after the fact. This paper describes the implementation of the SWEAP Investigation, the driving requirements for the suite, expected performance of the instruments, and planned data products, as of mission preliminary design review.

Wave-particle instabilities driven by departures from local thermodynamic equilibrium have been conjectured to play a role in governing solar wind dynamics. We calculate the statistical variation of linear stability over a large subset of Helios I and II observations of the fast solar wind using a numerical evaluation of the Nyquist stability criterion, accounting for multiple sources of free energy associated with protons and helium including temperature anisotropies and relative drifts. We find that 88% of the surveyed intervals are linearly unstable. The median growth rate of the unstable modes is within an order of magnitude of the turbulent transfer rate, fast enough to potentially impact the turbulent scale-to-scale energy transfer. This rate does not significantly change with radial distance, though the nature of the unstable modes, and which ion components are responsible for driving the instabilities, does vary. The effect of ion-ion collisions on stability is found to be significant; collisionally young wind is much more unstable than collisionally old wind, with very different kinds of instabilities present in the two kinds of wind.

Educational technology supports meaningful learning and enables the presentation of spatial and dynamic images, which portray relationships among complex concepts. The Technology-Enabled Active Learning (TEAL) Project at the Massachusetts Institute of Technology (MIT) involves media-rich software for simulation and visualization in freshman physics carried out in a specially redesigned classroom to facilitate group interaction. These technology-based learning materials are especially useful in electromagnetism to help students conceptualize phenomena and processes. This study analyzes the effects of the unique learning environment of the TEAL project on students' cognitive and affective outcomes. The assessment of the project included examining students' conceptual understanding before and after studying electromagnetism in a media-rich environment. We also investigated the effect of this environment on students' preferences regarding the various teaching methods. As part of the project, we developed pre-and posttests consisting of conceptual questions from standardized tests, as well as questions designed to assess the effect of visualizations and experiments. The research population consisted of 811 undergraduate students. It consisted of a small-and a large-scale experimental groups and a control group. TEAL students improved their conceptual understanding