Inversion of Stokes profiles from solar magnetic elements

We describe a new LTE inversion code for the analysis of Stokes profiles em erging from unresolved magnetic elements. It has been specifically designed to obtain the thermal, dynamic, and magnetic properties of these structure s in a self-consistent manner by fitting the whole shape of the observed sp ectra. The inversion code is based on a previous scheme by Ruiz Cobo & del Toro Iniesta and implements the thin flux-tube model as a reasonable descri ption of reality. All physical parameters considered relevant for the probl em (including velocity fields) are retrieved by means of a. Marquardt nonli near least-squares algorithm. We present the results of extensive tests aim ed at characterizing the behavior of the code so as to understand its limit ations for the analysis of real observations. The code is found to produce accurate results even with only two spectral lines and noisy Stokes I and V profiles. A detailed error treatment, in which the covariances between par ameters are explicitly included, is also carried out in order to investigat e the uniqueness and reliability of the inferred model atmospheres.