Abstract
High-quality measurements of electromagnetic fields and electron
velocity distributions by the Magnetospheric Multiscale (MMS) mission in
Earth’s magnetosheath present a unique opportunity to characterize
heliospheric plasma turbulence and to determine the mechanisms
responsible for its dissipation. We apply the field-particle correlation
technique to the MMS measurements to identify the dissipation mechanism
and quantify the dissipation rate. It is found that 95% of the
intervals have velocity-space signatures of electron Landau damping that
are quantitatively consistent with linear kinetic theory for the
collisionless damping of kinetic Alfvén waves. About 75% of the
intervals have asymmetric signatures, implying that often the
collisionless damping is stronger for waves propagating one direction
along the magnetic field than the other. Nearly half of the samples have
the same electron energization rates as order-of-magnitude estimates of
the turbulent energy cascade rate, suggesting that electron Landau
damping is frequently responsible for the dissipation of magnetosheath
turbulent energy.