Plasma dynamics and transport are studied experimentally in a multicell Penning-Malmberg trap. The goal is to develop methods for accumulation and long-term confinement of larger numbers of charged particles (e.g., positrons) than is presently possible. In this scheme, the particles constitute non-neutral plasmas which are confined separately in a parallel array of storage cells. Experiments are presented in which pure electron plasmas are transferred from a large-diameter “master cell” trapping region into four smaller, parallel “storage cells,” three of which are offset from the magnetic symmetry axis. The physics of the transfer process, as well as the confinement properties of plasmas in the storage cells, is discussed. We show that plasmas can be transferred into the storage cells and held there for up to a day or more using the rotating wall technique, provided that the plasma radius is sufficiently small compared to that of the cell wall. Experiments regarding the confinement of plasmas with kilovolt space charge are discussed. Recommendations are provided for future efforts with high-capacity multicell traps.

Experiments and vortex-in-cell simulations are used to study an initially axisymmetric, spatially distributed vortex subject to an externally imposed strain flow. The experiments use a magnetized pure electron plasma to model an inviscid two-dimensional fluid. The results are compared to a theory assuming an elliptical region of constant vorticity. For relatively flat vorticity profiles, the dynamics and stability threshold are in close quantitative agreement with the theory. Physics beyond the constant-vorticity model, such as vortex stripping, is investigated by studying the behavior of nonflat vorticity profiles.

Chirped-frequency autoresonant excitation of the diocotron mode is used to move electron plasmas confined in a Penning-Malmberg trap across the magnetic field for advanced plasma and antimatter applications. Plasmas of 10 8 electrons, with radii small compared to that of the confining electrodes, can be moved from the magnetic axis to !90% of the electrode radius with near unit efficiency and reliable angular positioning. Translations of !70% of the wall radius are possible for a wider range of plasma parameters. Details of this process, including phase and displacement oscillations in the plasma response and plasma expansion, are discussed, as well as possible extensions of the technique. V C 2015 AIP Publishing LLC. [http://dx.

The pulse from a transversely excited atmospheric CO(2) laser consists of a sharp spike followed by a long, drawn out tail region spanning about 2-5 micros caused by the nitrogen gas in the laser cavity. The nitrogen tail is undesirable in many applications because it decreases the average power of the laser pulse. We employ a pinhole plasma shutter for eliminating the nitrogen tail and shortening the pulse width. The pinhole shutter optically triggers plasma at a certain point in time with respect to the temporal profile of the laser pulse. This way, a good portion of the sharp spike is transmitted, while the energy stored in the nitrogen tail is consumed in heating the plasma. This simplistic plasma shutter is easy to build and inexpensive compared to other existing plasma shutter designs.

The perpendicular dynamics of a pure electron plasma column are investigated when the plasma spans two Penning-Malmberg traps with noncoinciding axes. The plasma executes noncircular orbits described by competing image-charge electric-field (diocotron) drifts from the two traps. A simple model is presented that predicts a set of nested orbits in agreement with observed plasma trajectories.