Reducing multiphoton ionization in a linearly polarized microwave field   by local control
  We present a control procedure to reduce the stochastic ionization of hydrogen atom in a strong microwave field by adding to the original Hamiltonian a comparatively small control term which might consist of an additional set of microwave fields. This modification restores select invariant tori in the dynamics and prevents ionization. We demonstrate the procedure on the one-dimensional model of microwave ionization. 
S. Huang, C. Chandre and T. Uzer