Radio-frequency preferential plugging of multi-ion-species plasma in cusped magnetic devices

The r.f. preferential plugging of multi-ion-species plasma is studied theoretically and experimentally in a magnetic-cusp plasma. In a He + , N + and plasma He + is effectively plugged in, while N + and are allowed to escape freely from a container by the applied r.f. field. In a H + , and plasma, all ion species are plugged in the container. These experiments can be explained by theory.