This project will advance fundamental understanding of how ion temperatures change during violent collisions. Extremely powerful lasers have been built in the US and elsewhere to create small, controlled nuclear reactions. These lasers are tightly focused to heat atoms to temperatures of millions of degrees and force them to collide violently. Understanding exactly how this process works is critical for optimizing future experiments in laser-driven nuclear reactions. This project will reproduce violent ion collisions in slow-motion in an experiment where the ion motion can be measured with extreme precision. In collaboration with theory specialists, the results will be used to validate computer simulations. These simulations, in turn, can then be applied to higher temperature laser-driven experiments with greater confidence. In addition to this important scientific contribution, this project will allow undergraduate and graduate students to participate in cutting-edge research in the field of plasma science.
The plasma generated in laser-driven high energy density (HED) experiments changes rapidly. The plasma is formed when a coated cryogenic solid deuterium-tritium fuel target is heated and compressed by laser energy. The plasma temperature rises from nearly absolute zero to millions of degrees and the density rises above solid-state density. Modeling collisions throughout this process requires many different approximations, complicating computer simulations of the rapidly changing environment. Experimental measurements of the electron and ion temperature and density are also challenging in such HED plasmas, due to both the violent physical conditions and the intensive modeling required to convert measured quantities into basic plasma properties. With appropriate temperature- and density-scaling, this research project will probe collision dynamics in some of these difficult-to-model and difficult-to-measure circumstances. The project will study energy transfer, radiative heating, and thermal relaxation in the strongly-coupled-plasma regime, over a range of initial densities and temperatures and for a few different geometries. The first task will be to measure momentum transfer and collisional heating in a dual-species ultracold neutral plasma. The second task will be aimed at measuring electron-ion energy relaxation in magnetized and unmagnetized ultracold neutral plasmas. ​Graduate and undergraduate students will be recruited and trained to work on the experiments.
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.
