Author: Wimmer-Schweingruber, R.F.
Paper Title Page
WEYO02 Experimental Results: Charge-state and Current-density Distribution at the Plasma Electrode of an ECR Ion Source 101
 
  • L. Panitzsch, T. Peleikis, M. Stalder, R.F. Wimmer-Schweingruber
    IEAP, Kiel, Germany
 
  We have measured the current-density in very close vicinity (15 mm downstream) of the plasma electrode of our hexapole-geometry electron-cyclotron-resonance ion source (ECRIS). For this, we equipped our 3D-movable puller electrode with a customized Faraday Cup (FC) inside. To achieve high spatial resolution we reduced the aperture of the puller electrode to only 0.5 mm. Thus, the source-region of the extracted ion beam is limited to a very small area of the plasma electrode's hole (d = 4 mm). The information about the charge-state distribution and the current density in the plane of the plasma electrode is conserved in the ion beam and was scanned by remotely moving the small-aperture puller electrode (incl. FC) across the aperture of the plasma electrode. From additional m/q- measurements for the different positions we can deduce that different ion charge-states are grouped into bloated triangles of different sizes but with the same orientation in the plane of the plasma electrode with the current density peaking at the centre. This confirms simulations by various groups as well as some emittance measurements, but adds spatial resolution for the different charge-states.  
slides icon Slides WEYO02 [2.298 MB]