Structures and Electric Fields in Laser-Induced Magnetized Plasmas

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Ionized gases, or plasmas, are ubiquitous in nature, for example in lightning, the ionosphere, the sun, and many astrophysical environments. Plasmas are also common in technologies such as gas discharge lamps, microfabrication processes, fusion plasmas, combustion engines, and Hall thrusters. This project will develop new methods based on atomic spectroscopy to monitor the electric and magnetic fields inside of laser-generated laboratory plasmas. This is important because plasma fields are notoriously difficult to monitor, especially for small volumes of plasma, without influencing the particle distributions and fields. The research will pioneer novel quantum technologies that provide non-invasive plasma diagnostics. Shock fronts and ordered structures in plasmas will be studied, as well as the effects of magnetic fields on plasma dynamics. Due to the importance of plasmas in technology, plasma-physics research such as this drives advances in economic competitiveness and prosperity, national defense, space exploration, and communications. It also promotes progress in basic plasma science and astrophysics. Students affiliated with this project will get training that will help them prepare for careers in science, industry and education. This study is on small-scale, magnetized, and potentially strongly-coupled, plasmas obtained by laser-induced photo-ionization of atomic vapors. Both trapped atoms and room-temperature alkali-atom vapor cells will be used. As the photo-generated plasmas expand, they form shock fronts, and in the case of sufficiently strong coupling between ions and electrons the plasmas are expected to develop correlations with crystal-like order. This project will pioneer novel ways to make position- and time-resolved measurements of the expansion, the shock fronts, and the ordered structures in plasmas. A diagnostic method will be developed using laser spectroscopy with Rydberg atoms and electromagnetically-induced transparency (EIT). Electric fields in the plasma will be mapped via Rydberg-EIT spectroscopy. Another diagnostic will use micro-channel plates to count particles that are extracted from the plasma after a variable delay. The use of field-sensitive Rydberg-state tracer atoms embedded in the plasma as an all-optical diagnostic of macroscopic and random (Holtsmark) electric fields in plasmas may impact other fields in which magnetized plasmas occur, for instance in astrophysics, inertial-confinement and magnetic-confinement fusion, z-pinch studies, and ion trapping. Graduate and undergraduate students working on this project will be trained in atomic and plasma physics research, research presentation, and peer instruction. Students will also gain experience in the construction and operation of scientific apparatus.