  Superconducting 2H-NbSe2 single crystals show intrinsic low pinning values.
Therefore, they are ideal materials with which to explore fundamental
properties of vortices. (V, I) characteristics are the experimental data we
have used to investigate the dissipation mechanisms in a rectangular shape
2H-NbSe2 single crystal. Particularly, we have studied dissipation behavior
with magnetic fields applied in the plane of the crystal and parallel to the
injected currents, i.e. in the force-free state where the vortex helical
instability governs the vortex dynamics. In this regime, the data follow the
elliptic critical state model and the voltage dissipation shows an exponential
dependence.Moreover, this exponential dependence can be observed for in-plane
applied magnetic fields up to 40 degrees off the current direction, which
implies that the vortex helical instability plays a role in dissipation even
out of the force-free configuration.
