Abstract: In an apparatus for the doping of vessel supports (stents) with radioactive and non-radioactive atoms comprising an electron-cyclotron-ion-source (ECRIS) with an arrangement for extracting an ion beam from the ECRIS, a magnetic separation device for the splitting of the ion beam arranged in a downstream area of the extracted ion beam and an irradiation chamber in which the vessel supports are exposed to the selected partial ion beam, the ECRIS includes a microwave-permeable plasma chamber with a magnetic, six-pole arrangement, an electrically conductive tube portion disposed within the plasma chamber co-axially with the six-pole arrangement and having an in-coupling opening and also being axially movable for an adjustment of an optimal in-coupling and a co-axial cable extends through the in-coupling opening and has an outer sleeve which is in electrical contact and an inner conductor which is electrically insulated and forms at the inner wall of the tube a flat loop whose end is in contact with the tube wall.