  Collisionless dissipation of macroscopic energy into heat is an unsolved
problem of space and astrophysical plasmas, e.g., solar wind and Earth's
magnetosheath. The most viable process under consideration is the
turbulent-cascade of macroscopic energy to kinetic-scales where
collisionless-plasma-processes dissipate the energy. Space observations and
numerical simulations show the formation of kinetic scale current sheets in
turbulent plasmas. Instabilities in these CS can provide collisionless
dissipation and influence the turbulence. Spatial gradients of physical
quantities and non-Maxwellian velocity distribution functions provide the
free-energy-sources for CS plasma instabilities. To determine the
free-energy-sources provided by the spatial gradients of plasma density and
electron/ion bulk velocities in CS formed in collisionless turbulent plasmas
with an external magnetic field $\mathbf{B}_0$, we carried out two-dimensional
PIC-hybrid simulations and interpret the results within the limitations of the
simulation model.
  We found that ion-scale CS in a collisionless turbulent plasma are formed
primarily by electron shear flows, i.e., electron bulk velocity inside CS is
much larger than ion bulk velocity while the density variations through the CS
are relatively small ($<$ 10\%). The electron-bulk-velocity and, thus, the
current density inside the sheets are directed mainly parallel to
$\mathbf{B}_0$. The shear in the perpendicular electron- and
ion-bulk-velocities generates parallel electron- and ion-flow-vorticities.
Inside CS, parallel electron-flow-vorticity exceeds the parallel
ion-flow-vorticity, changes sign around the CS centers and peaks near the CS
edges. An ion temperature anisotropy develops near CS during the CS formation.
It has positive correlation with the parallel ion- and
electron-flow-vorticities. Theoretical estimates support the simulation
results.
