Recent milestones from the APEX Collaboration, on the path toward confined e+e- pair plasmas*

The goal of APEX (A Positron Electron eXperiment) is to create and study cold (~1 eV or less), confined, strongly magnetized (r_L < λ_D), matter-antimatter “pair plasmas” in the laboratory. This is a compelling objective in fundamental plasma physics, as the mass symmetry of such systems is expected to dramatically simplify/reduce the available modes. Our path to pair plasmas involves joining together and further developing state-of-the-art physics and engineering in several areas; here, we present an overview of some recent highlights. In the area of e+ beam physics, we have demonstrated a technique for combining e+ remoderation with ExB drift injection (so as to enable injection of lower-energy e+ into stronger B fields). We also recently injected short (76-ns) bunches into a dipole magnetic field; this resulted in orders of magnitude more trapped e+ than possible with a DC beam, as well as a platform for testing newly developed gamma diagnostic methods. In the area of non-neutral plasma physics, we have achieved effective cooling, stacking, long confinement times, and essentially lossless transfer protocols for e- plasmas in several of the Penning-Malmberg traps that we employ. Meanwhile, the design and engineering of our two tabletop-sized e+e- pair plasma traps --- a levitated dipole and an optimized stellarator --- are at the leading edge of non-insulated HTS (high-temperature superconducting) coil development and stellarator optimization. Finally, we will outline the plans for the next year(s) of APEX, during which we will continue to assemble the pieces of the pair plasma "puzzle" (experimental systems, enabling techniques, and theory/simulation predictions for our specific geometries and regimes).