RUI: Multipole Plasma Trap Proof of Concept Investigation

University Of Alaska Anchorage Campus, Anchorage AK

Investigators

Abstract

The goal of this research is to investigate a new concept for containing a plasma, the Multipole Plasma Trap (MPT) concept. Plasma is a state of matter similar to a gas but consisting of electrically charged particles such as electrons and ions. The MPT is a structure of specially shaped electrodes that creates electrical conditions in which the plasma particles may be contained due to the focusing effect of rapidly varying voltage applied between the electrodes. The ability of the MPT to trap various kinds of plasma for laboratory studies will be explored by conducting experiments and computer simulations. The MPT project at the University of Alaska Anchorage (UAA) is the centerpiece of the UAA Plasma Lab, which supports undergraduate research experience across several STEM fields. Plasma science and engineering is a rapidly growing, multidisciplinary field, with many basic physics questions to be answered as well as technological applications to be developed. The UAA community, ranging from students working directly on the project to broader K-12 and general public audiences, will observe and participate in the MPT research, will see the benefits and opportunities of STEM education and careers, and will make connections with plasma science and engineering in particular. This research is an experimental and computational study of the trapping of quasi-neutral plasma by three-dimensional (3D), time-varying electric multipole fields. Prior work has shown that radio-frequency (RF) structures of varying multipole order can trap various plasma configurations, consisting of ions only, electrons and ions, or pair and antimatter plasma components. The multipole field is chosen predominantly to interact strongly with light particles but negligibly with heavy ones. Two-dimensional particle-in-cell (PIC) modeling has shown that the light species experiences a pseudopotential well, with overall space charge neutralized by the heavy species, and the modeling has defined particular multipole and plasma configurations of interest for detailed 3D PIC modeling and first experimental tests of this Multipole Plasma Trap concept. The behavior of marginally stable particles at the plasma edge and RF sheath, as well as ponderomotive gyroresonance effects, are new topics to be studied. The proof of concept experiment will utilize a hexadecapole structure in an ultrahigh vacuum chamber to trap plasma consisting of light positive ions and heavy negative ions, as well as positive ions and electrons, and it will investigate loading the trap via ion sources and diagnosing trapped plasma characteristics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.