  We explain the meaning of dynamical manipulation, and we illustrate its
mechanism by using a system composed of a charged particle in a Penning trap.
It is shown that by means of appropriate electric shocks (delta-like pulses)
applied to the trap walls one can induce the squeezing transformation. The
geometric phases associated to some cyclic evolutions, induced either by the
standard fields of the Penning trap or by the superposition of these plus a
rotating magnetic field, are analysed
