New Mechanism for Single-Component Plasma Loss from Asymmetric Potentials

The manipulation of single-component plasmas in a Penning-Malmberg trap often requires the use of applied asymmetric potentials.\footnote{Huang, et. al., {\it Phys. Rev. Lett.} {\bf 78}, 875 (1997).}$^,$\footnote{\small Fajans, Gilson, Friedland, {\it Phys. Rev. Lett.} {\bf 82}, 4444 (1999).}$^,$\footnote{Hurst, Danielson, Baker, Surko, {\it Phys. Rev. Lett.}, {\bf 113} 025004 (2014).} While it has long been known that these asymmetries can cause plasma expansion,\footnote{Kriesel and Driscoll, {\it Phys. Rev. Lett.} {\bf 85}, 2510 (2000).} it is shown here that direct particle loss may also occur; and this is deleterious for many applications, especially antimatter storage. The plasma self-potential and the applied potential superpose to form a separatrix, and this can result in the $E\times B$ drift of plasma particles out of the trap. A simple model is presented which captures the observed behavior. The analogy of this effect to the stripping of a 2D vortex by a shear flow will be discussed.