  Long-range interacting Hamiltonian systems are believed to relax generically
towards non-equilibrium states called "quasi-stationary" because they evolve
towards thermodynamic equilibrium very slowly, on a time-scale diverging with
particle number. We show here that, by applying a suitable perturbation
operator for a finite time interval, we obtain, in a family of long-range
systems, non-equilibrium states which appear to be strictly stationary. They
exist even in the case of a harmonic potential, and are characterised by an
ordered microscopic phase space structure. We give some simple heuristic
arguments which predict reasonably well some properties of these states.
