  We study N=2 supersymmetric Abelian gauge model with the Fayet-Iliopoulos
term and an arbitrary number of chiral matter multiplets in two dimensions. By
analyzing the instanton contribution we compute the non-perturbative
corrections to the mass spectrum of the theory and the quantum deformation of
the classical vacua space. In contrast to known examples the non-perturbative
bosonic potential is saturated by the one-instanton contribution and can be
directly found within the semiclassical expansion around the one-instanton
saddle point.
