Figure 3
Ray-tracing simulations of a full 3D model of the dodecapole bandpass filter, integrated into the lens system of the ToF-MM at beamline P22 of PETRA III. (a) A scaled view (scale bar is 50 mm) of the bandpass filter, consisting of entrance aperture (in plane GP1), lens 2A, fringe field correctors F1 and F2 framing the dodecapole, lens 2B and exit aperture (plane GP2). Equipotential contours for the lens fields are in blue and for the dodecapole are in red. (b) A close-up view of the region near the exit aperture for five different energies: Ekin = Epass = 580 eV (black rays) and faster (blue rays) and slower electrons (red rays) with ΔE varied in steps of 40 eV. (c) A view including lens 1 and lens 3 with the radial coordinate stretched. The dashed rectangle marks the region shown in (d) after dewarping (conformal scale). (e) A series of calculated transmission profiles; see the main text for details. (Ray tracing using SIMION 8.0; Dahl et al., 2007.) |