Hollow Ions in Pulsed Power Plasmas and their Unique Applications

Advancing the frontiers of knowledge in plasma and atomic physics is vital for understanding the Universe, where plasma is the most common state of observable matter, and for advancing new technologies including fusion energy. Over the last decade, observations of short-lived extreme states of matter such as ''hollow ions'' -- ions missing their innermost electrons while retaining outer ones -- have been made possible by very active research conducted on x-ray free-electron lasers and by substantial increases in the laser power. It was recently shown that these unique states of matter can also be created using pulsed power plasmas. Based on a deeper knowledge of how hollow ions are formed and behave, powerful new tools for examining other complex, high-energy-density plasma environments can be developed. This award will contribute both to advancing knowledge in dense plasma and atomic physics, and to the development of plasma science and technology workforce, which is in high demand. The goals of this project are defined as the achievement of better understanding of the nature of hollow ions, regarded as exotic states of matter in pulsed power plasmas, and the development of their unique applications for moderate- and high-density plasmas. This will be accomplished through a continued search for new spectral features from hollow ions specific to pulsed power plasmas, along with the analysis and modeling of relevant experimental data. Additionally, a possible connection between the generation of nonthermal electrons and hollow ions will be investigated, and plasma non-uniformity and charge-exchange processes will be studied. The comprehensive modeling and analysis of X-ray emissions from these ions is anticipated to provide fundamental insights into their formation pathways, potentially enabling their use for new advanced diagnostics for hot and warm dense matter. 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.