Plasma turbulence is studied via direct numerical simulations in a two-dimensional spatial geometry.
Using a hybrid Vlasov-Maxwell model, we investigate the possibility of a velocity-space cascade.
A novel theory of space plasma turbulence has been recently proposed by Servidio et al.
[Phys. Rev. Lett. 119, 205101 (2017)], supported by a three-dimensional Hermite decomposition
applied to spacecraft measurements, showing that velocity space fluctuations of the ion velocity
distribution follow a broad-band, power-law Hermite spectrum P(m), where m is the Hermite index.
We numerically explore these mechanisms in a more magnetized regime. We find that (1) the
plasma reveals spectral anisotropy in velocity space, due to the presence of an external magnetic
field (analogous to spatial anisotropy of fluid and plasma turbulence); (2) the distribution of energy
follows the prediction PðmÞ m2, proposed in the above theoretical-observational work; and (3)
the velocity-space activity is intermittent in space, being enhanced close to coherent structures
such as the reconnecting current sheets produced by turbulence. These results may be relevant to
the nonlinear dynamics weakly collisional plasma in a wide variety of circumstances.