  We propose a way of fast switching the chirality in a magnetic nanodisk by
applying a field pulse. To break the symmetry with respect to clockwise or
counterclockwise chirality a mask is added by which an inhomogeneous field
influences the vortex state of a nanodisk. Using numerical spin--lattice
simulations we demonstrate that chirality can be controllably switched by a
field pulse, whose intensity is above some critical value. A mathematical
definition for the chirality of an arbitrary shaped particle is proposed.
