f0 50[Hz] "电源频率" Ni 960 "内线圈匝数" No 576 "外线圈匝数" sigma 3.4e7[S/m] "铝的电导率" I0 20[A] "线圈电流" d_wire 1.2[mm] "线圈线径" M_disc 0.107[kg] "铝盘质量" z0 3.8[mm] "铝盘初始位置"