Magnetic helicity in the solar wind Original Research Article

Magnetic helicity measurements in the solar wind are a useful diagnostic for a wide range of physical processes. The helicity has been related to magnetic flux rope ejection at the sun, wave instabilities driven by energetic particles, interplanetary turbulence dynamics, and dissipation to name just four classes of observations. We will review magnetic helicity observations in the solar wind spanning a wide range of heliocentric distances, latitudes, spatial scales, and dynamical processes in an effort to determine what is typical of the helicity spectrum and what can be viewed as a signature of identifiable dynamical processes.