Absolute Photoionization Cross Section of K+ Ions. F. Folkmann, H. Kjeldsen, H. Knudsen, M.S.Rasmussen, J.B.West(x), and T.Andersen Institute of Physics and Astronomy, University of Aarhus, Denmark x)Daresbury Laboratory, UK The absolute photoionization cross section of the K+ ion has been measured within the photon energy range 31-47 eV applying the undulator beamline at the ASTRID storage ring. In addition, the structural properties of the 3s-np(n=4-6) window resonances have been determined with improved accuracy compared to the recent data obtained with the dual plasma technique.