Scott Baalrud, a professor in the U-M Department of Nuclear Engineering & Radiological Sciences, has received funding to research high-energy-density plasmas.
Baalrud’s project, “Dynamic Structure of Magnetized High-energy Density Plasmas,” is one of 21 High-Energy-Density Laboratory Plasmas (HEDLP) projects selected to receive funding from the Department of Energy’s (DOE) Office of Science (SC) in collaboration with the National Nuclear Security Administration (NNSA).
High-Energy-Density Laboratory Plasmas (HEDLP) research explores the behavior of ionized matter at extreme conditions such as high temperature, density, or pressure. According to DOE, researchers apply these studies to fields including astrophysics, nuclear and particle physics, medicine, national security, and plasma science.
“Magnetized HEDLPs are a frontier area of physics research,” said Baalrud. “Recent advances in high-intensity lasers and pulsed power generators have made it possible to simultaneously compress matter to the highest pressures found on Earth (millions of atmospheres), and magnetic fields to the highest field strengths found on Earth (tens of thousands of Tesla).”
“In doing so, HEDLPs create an exotic state of magnetized matter that is otherwise found only in dense astrophysical objects, such as the atmosphere of a magnetar,” Baalrud continued. “Little is known about this state of matter. Exploration is likely to reveal new physics that might eventually lead to unanticipated technological applications, perhaps in fusion energy research or radiation sources. The ability to create this exotic state of matter on Earth also makes it possible to perform a new category of laboratory astrophysics.”
Baalrud’s proposed research will use theory and computation to explore a particularly novel state of magnetized high energy density plasma in which the plasma is so dense that it is strongly coupled, and is in the presence of such a strong magnetic field that it is strongly magnetized.
“Most plasmas are weakly coupled in the sense that they behave like dilute ionized gases,” said Baalrud. “Strongly coupled plasmas are fundamentally different in that they are dense enough to behave more like ionized supercritical fluids, or liquids, rather than gases. Similarly, most plasmas are weakly magnetized in the sense that the gyromotion of particles occurs at a scale that is much larger than the scale at which particles interact with one another (the Debye length). Strongly magnetized plasmas are those in which the magnetic field is so strong that gyromotion occurs at the scale of interactions. Combined, these effects lead to a novel state of matter that we are just beginning to explore.”
Baalrud’s proposed research will develop a theory to explain the basic properties of this state of matter and will use molecular dynamics, a first-principles simulation technique, to test the predictions of the theory. These will be focused on predicting the dynamic structure-function.
The dynamic structure-function is chosen as the focus of this study because it contains a wealth of information about the transport properties of the plasma, and it is the most likely quantity to be measured in future experiments (via x-ray Thompson scattering).
Interpreting these experiments will require a theoretical description of the dynamic structure-function, which is related to the measured scattering spectrum. Such a description does not yet exist. The proposed research intends to fill this gap in our understanding.