quadrupole
/ˈkwɒdrʊpəʊl/noun
1- Physics a distribution of electric charge or magnetization consisting of four equal monopoles, or two equal dipoles, arranged close together with alternating polarity and operating as a unit【物理】四极。
1.1
- a device using such an arrangement directed at one point to focus beams of subatomic particles四极聚向设备。