Design and Construction of a 21-cell Multicell Trap for Positron Storage

There are many potential applications of high-capacity and/or portable antimatter traps. We describe the construction (in progress) of a novel multicell Penning-Malmberg (PM) trap designed to store up to $10^{12}$ positrons.\footnote{Danielson, Weber, Surko, {\it Phys. Plasmas} {\bf 13}, 123502 (2006).}$^,$\footnote{Danielson, Hurst, Surko, AIP Conf. Proc. {\bf 1521}, 101 (2013).} The device consists of 21 PM cells (in three banks of 7 cells) within a UHV vacuum system and a 140~mm diameter warm-bore, 5 tesla, magnet. Each cell will use kV confinement potentials and have an azimuthally segmented electrode for diagnostics and plasma manipulation, such as the application of rotating electric fields. An independent, large-diameter master cell will be used to move plasmas, received from a buffer-gas positron accumulator, across the magnetic field to the off-axis cells using autoresonant diocotron-mode excitation.\footnote{Fajans, Gilson, Friedland, {\it Phys. Rev. Lett.} {\bf 82}, 4444 (1999).} Details of the current design will be presented, as well as scenarios for effective extraction and use of the trapped particles.