Fig. 1. Structure of an ideal Penning trap

Fig. 2. Geometry model of a Penning trap in ANSYS

Fig. 3. Contour of equal potential for the electric field in the gap of the Penning trap (1/4 of the whole plane)

Fig. 4. Tracking results for an ion moving in an ideal Penning trap (start from x=0.1 cm, y=0 and z=0.2 cm)

Fig. 5. The tracking results for an ion moving in the Penning trap, with Helium gas filled in (start from x=0.1 cm, y=0 and z=0.2 cm)

Fig. 6. The way to apply the quadrupole excitation potential on the ring electrodes

Fig. 7. Tracking results for an ion moving in the Penning trap, with helium gas filled in and quadrupole electric potential applied (start from x=0.1 cm, y=0 and z=0.2 cm), here 潘宁装置中充入He气体加四极场激发时离子运动轨迹图（ ）（初始位置x=0.1 cm，y=0，z=0.2 cm）

Fig. 8. Equal potential distribution when the excitation potential of ±10 V applied on the ring electrodes

Fig. 9. Relative error between the real distribution of the potential of the gap and the ideal quadruapole distribution, varying with different radii

Fig. 10. Diagram of the ring electrodes for an optimized Penning trap

Fig. 11. Projection of the motion of an ion upon x-y plane, the starting point is x=0.1 cm and y=0 cm