En Route to Electron/Positron Pair Plasmas
The large mass imbalance between ions and electrons — and the resulting separation of the two species' length and time scales — is a cornerstone of traditional plasma physics. Therefore, to consider the novel behavior of a "pair plasma", comprising particles with opposite charge but equal mass, is to revisit much of plasma physics from the ground up. To date, on the order of 1000 papers have explored this topic, including a variety of analytical and computational treatments, but the experimental side of the investigation is still in its nascence. Laboratory creation and confinement of electron/positron plasmas will enable the first tests of many simulation and theory predictions, with implications for our understanding not only of pair plasmas (and astrophysical phenomena in which they play a role) but also of traditional electron/ion plasmas. This is the goal of the APEX/PAX project, in which a world-class cold positron beam (NEPOMUC) is being combined with state-of-the-art techniques from non-neutral plasma physics. Significant milestones have been achieved in the past couple years, including the demonstration of efficient injection and subsequent confinement of cold positrons in a dipole magnetic field.
The process is now underway to upgrade from the prototype experiment to a levitated HTSC (high-temperature superconductor) coil suitable for the simultaneous confinement of electrons and positrons.
**Refreshments will be served at 3:45pm in Spalding 113.