Kugeler, O. Junginger, T. Knobloch, J. Krzyzagorski, M.M. Köszegi, J.M. Riik, L. Treimer, W. Ziesche, R.F. JACoW Geneva, Switzerland 978-3-95450-191-5 10.18429/JACoW-SRF2017-THPB017 English 762-765 THPB017 ion neutron niobium experiment detector Contribution to a conference proceedings 2018 2018-01 https://doi.org/10.18429/JACoW-SRF2017-THPB017 http://jacow.org/srf2017/papers/thpb017.pdf The dynamics of flux expulsion in Nb samples during superconducting transition has been investigated with neutron radiography. Aiming at a reduction of the trapped flux with respect to obtaining a small residual resistance it was attempted to influence the expulsion by applying external AC magnetic fields. The results of these experiments are presented.