Study of species separation and field-penetration in a multi-component plasma

Summary form only given, as follows. The interaction of a magnetic field with a multi-component plasma is a topic of particular relevance for understanding the physics of the plasma opening switch (POS). Results from a recent POS experiment show that a current channel propagates into the POS plasma. As the current channel propagates, the hydrogen plasma component is pushed ahead of, and separates from, the current front, a phenomenon known as species separation. At the same time, the more massive carbon component is left behind the front with very little current flowing through it, a phenomenon known as magnetic field penetration. The observed current front is also broad. In this talk, we will present results from particle-in-cell simulations in which the field penetration and species separation are observed. In these simulations a positive potential hill associated with the J/spl times/B force develops that, in the frame of the moving hill, reflects the lighter ions but is not large enough to reflect heavier ions. The current channel can propagate in this fashion because the positive charge associated with the heavier species is neutralized by electron space charge that fills in behind the front. In these simulations, the boundaries provide a source of electrons that are born in the magnetic field and are responsible for providing space-charge neutralization of the heavier magnetized species that is left behind. Simulations show that species separation is not possible without these electrons. Also, the simulations show that the field does not penetrate; i.e., the current front does not propagate into the plasma while leaving plasma behind, without species separation. We will also examine how the energy flow into the plasma is partitioned.