  Within Density Functional theory, we investigate stationary many-vortex
structures in a rotating $^4$He nanocylinder at zero temperature. We compute
the stability diagram and compare our results with the classical model of
vortical lines in an inviscid and incompressible fluid. Scaling the results to
millimeter-size buckets, they can be compared with experiments on vortex arrays
conducted in the past. Motivated by recent experiments that have used atomic
impurities as a means of visualizing vortices in superfluid $^4$He droplets, we
have also considered the formation of chains of xenon atoms along a vortex line
and the interaction between xenon atoms inside the same vortex and on different
neighboring vortex lines.
