Heavy Quark Production Measurements at THERA

The total cross sections of charm and beauty production at a future high-energy ep collider, THERA, are expected to increase by factors of three and five, respectively, as compared to HERA. Heavy quarks can be measured at THERA in wide ranges of transverse momenta and Q^2 values, thereby providing a solid basis for testing the perturbative QCD calculations. The charm and beauty contributions to the proton structure can be probed at THERA at ~1 order of magnitude smaller Bjorken x values with respect to those at HERA. Charm production in the process of photon-gluon fusion at THERA can serve for the determination of the gluon structure of the proton in the as yet unexplored kinematic range 10^{-5} < x_g < 10^{-4}. The cross section of charm production in charged current at THERA is ~1 order of magnitude larger than that at HERA.