RUI: approach to thermal equilibrium for electron plasma in non-uniform magnetic field traps

The National Science Foundation awarded Lawrence University of Wisconsin a $431,200 Project Grant under the Mathematical and Physical Sciences program (CFDA 47.049) to explore thermal equilibrium states for electron plasma in non-uniform magnetic field traps from June 2022 to May 2025. Specifically, the university will test theories on whether thermal equilibrium exists for more complex magnetic geometries like a toroidal or dipole magnetic field. It will develop an electron plasma target for injection of positrons to create a positron-electron plasma in a levitated dipole field. The results of this research aim to further understanding of the role of trap symmetry for plasmas and help develop matter-antimatter plasmas relevant to neutron stars and the early universe. The award also supports engaging undergraduate students in the research effort to integrate research and education outcomes.

Abstract

This project seeks to explore how large collections of electrons can be trapped with different magnetic bottles. The results will be important for extending our understanding of the role of the symmetry of traps for plasmas and will help US make matter-antimatter plasmas, a unique kind of plasma that exists around neutron STARS and that existed in the early universe. The project will also integrate research and education by engaging undergraduate students in the effort. Non-neutral plasmas confined in uniform magnetic field traps can come to thermal equilibrium and be confined indefinitely. Such thermal equilibrium states are understood in terms of symmetry of the system, namely the conservation of canonical angular momentum. IT is not clear whether such states exist for more complicated magnetic geometries; existing theory suggests they do not exist in a toroidal magnetic field, but that they may exist for a dipole magnetic field. This project seeks to test these theories and to develop a suitable electron plasma target for injection of positrons and creation of a positron-electron plasma in a levitated dipole field. 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.