Abstract:
Solar wind turbulence within high-speed streams is reviewed from the point of view of
embedded single nonlinear Alfvén wave cycles, discontinuities, magnetic decreases (MDs), and shocks. For
comparison and guidance, cometary plasma turbulence is also briefly reviewed. It is demonstrated that
cometary nonlinear magnetosonic waves phase-steepen, with a right-hand circular polarized foreshortened
front and an elongated, compressive trailing edge. The former part is a form of “wave breaking” and the latter
that of “period doubling.” Interplanetary nonlinear Alfvén waves, which are arc polarized, have a ~180°
foreshortened front and with an elongated trailing edge. Alfvén waves have polarizations different from
those of cometary magnetosonic waves, indicating that helicity is a durable feature of plasma turbulence.
Interplanetary Alfvén waves are noted to be spherical waves, suggesting the possibility of additional local
generation. They kinetically dissipate, forming MDs, indicating that the solar wind is partially “compressive”
and static. The ~2 MeV protons can nonresonantly interact with MDs leading to rapid cross-field (~5.5%
Bohm) diffusion. The possibility of local (~1 AU) generation of Alfvén waves may make it difficult to forecast
High-Intensity, Long-Duration AE Activity and relativistic magnetospheric electrons with great accuracy. The
future Solar Orbiter and Solar Probe Plus missions should be able to not only test these ideas but to also
extend our knowledge of plasma turbulence evolution.
