Cross helicity in the kinetic range of plasma turbulence using MMS

Cross helicity is an invariant of ideal magnetohydrodynamics. However, the ideal approximation breaks down close to kinetic scales and cross helicity is not an invariant of the system any more. Historically spacecraft have not had high enough time resolution to study the behavior of cross helicity approaching kinetic scales. MMS with its high cadence plasma data from Fast Plasma Instument (FPI) allows us to explore this approach to kinetic scales. We study cross-helicity spectra using single and multi-spacecraft methods and discuss the evolution of alignment as described by cross helicity. Two cases studies, one from the magnetosheath and another one from the solar wind are presented.