Fig. 1

Overall structure of the trap. (a) Electrode arrangement and sizes are shown. Two RF electrodes, four End DC electrodes, six Middle DC electrodes, and one Center DC electrode are symmetrically arranged. (b) Image of the through-hole. The hole is located at the center of the trap and has a square shape with a side length of 40 \(\mathrm {\,\mu m}\). The Ca beam is introduced through this hole.