Plasma & HED Physics - Laboratory for Laser Energetics

Fundamental Physics at Extreme Conditions

The success of all laser-plasma applications relies on the detailed understanding of plasmas—the fourth state of matter—and how lasers interact with them. Plasmas make up over 99% of the matter in the universe, but only a fraction of matter on earth.

Plasma and high-energy-density (HED) physics seek to understand this fourth state of matter at a fundamental level. Because of the significant amount of energy that a laser can deposit into a small volume, it is experimental facilities like OMEGA and OMEGA EP let us create and study materials that would only exist in the extreme astrophysical environments found throughout the cosmos.

An artistic depiction of an accretion disk.

What is HED Physics?

High energy density (HED) physics is the study of matter and radiation under extreme conditions of pressure, temperature, and density.

At HED conditions, matter can be heated to millions of degrees, compressed to many times the density of solids, and transition into a fourth state known as plasma. These extreme states are common in the universe but require powerful energy drivers, such as high-intensity lasers, particle beams, or pulsed power machines, to be created in a laboratory.

Exploring Extreme States of Matter

At the end of the 20th century, physicist Hugh Van Horn outlined grand challenges in probing the behavior of matter under astrophysical conditions. What happens when atoms are squeezed so closely together that their separations are smaller than fundamental quantum scales like the de Broglie wavelength or the Bohr radius? How can we describe matter when its thermal, Fermi, and Coulomb energies are all comparable—conditions where familiar tools of condensed matter or plasma physics break down?

Today, with powerful laser facilities such as OMEGA and exascale high-performance supercomputers, researchers access these extreme regimes in experiments and to understand the exotic physics of matter through large-scale first-principles calculations. Exploring them not only pushes the frontiers of physics to describe the most extreme environments in the universe, but also sharpens the models used to predict the performance of fusion implosions.

Mitigating Laser–Plasma Instabilities

When scientists first used powerful lasers to create plasmas, they quickly discovered a fundamental obstacle.

Because a plasma is a collective medium—where the laser’s oscillating electromagnetic field launches waves that radiate, amplify, collide, and reverberate throughout the system—an array of complex effects emerge. These “laser–plasma instabilities” scatter energy, disrupt compression and pose one of the central challenges to achieving fusion in the lab.

That’s why researchers in inertial confinement fusion and high-energy-density science have devoted decades to understanding—and finding ways to control—these instabilities in order to realize fusion in the laboratory.

A Multidisciplinary Approach

LLE plays a critical role in plasma and HED physics by adopting a multidisciplinary approach that combines the expertise of physicists, laser scientists, engineers, computer scientists, and operations. It is precisely this approach that enables LLE to chart new frontiers in the creation and manipulation of extreme states of matter for fundamental science and applications.

Students from the University of Rochester and other academic institutions jumpstart their careers by participating in plasma research and ultrafast laser science and engineering.

Learn more about our graduate program and connect with a mentor.

Graduate Program

Research Areas

Laser–Plasma Interactions

At LLE, scientists explore how laser beams travel through and interact with plasma—knowledge crucial for mastering many advanced laser applications. Nearly all grand challenge laser-plasma applications require control of the laser propagation to optimize performance.

A key focus is studying, through both computer simulations and experiments, how adding bandwidth to laser beams can reduce disruptive plasma instabilities and improve laser performance. This work not only drives progress toward achieving inertial confinement fusion but also supports national security through the NNSA’s Stockpile Stewardship Program and fosters innovation in materials science, astrophysics, and advanced laser technology.

Ultrafast Plasma Photonics

Ultrafast photoionization with femtosecond lasers can generate both terahertz and XUV radiation that can be used to study fundamental light-matter interactions or as a probe for high-energy density physics. Spatiotemporal control (i.e., flying focus) and novel mid-IR laser systems are being used to explore innovative methods to control and enhance these laser-based sources.

Spatiotemporal pulse shaping is being pioneered at LLE, and in 2017 the “flying focus” was invented. This invention opened a new field of study for advanced laser-plasma applications, including a novel concept for TeV electron acceleration for future high-energy physics colliders.

Relativistic Laser-Plasma Science

Light exceeding an intensity of 10^18 W/cm^2 rapidly accelerates electrons to relativistic velocities, unlocking a novel regime of relativistic laser-matter interactions. LLE’s scientists use our world-class short-pulse laser facilities OMEGA-EP and MTW-OPAL to study the physics of these interactions and the technological applications they promise, such as relativistic transparency of plasmas; efficient and rapid acceleration of electron and ions; use of plasmas for laser amplification and lensing; and generation of efficient and bright x-ray and gamma-ray sources. LLE aims to study the fundamental physics of these extreme interactions, use them to create new plasma technologies and diagnostic techniques, and mentor the next generation of scientists in research using ultra-intense lasers.

On the frontier, we are preparing to use the proposed 25-petawatt NSF-OPAL laser to generate groundbreaking sources such as single-stage-to-100 GeV electron acceleration; and to probe novel quantum electrodynamic phenomena that become accessible at even higher intensity (» 10^24 W/cm^2) such as light-by-light scattering and generation of relativistic electron-positron plasmas.

High-Pressure Materials Science

Research at LLE and around the world is disrupting traditional perspectives for modeling, predicting, and controlling high-pressure material properties. These pioneering developments are occurring in three broad areas: extreme chemistry, warm dense matter, and X-Matter.

LLE’s high-pressure materials research goals are twofold: (1) to explore material properties and improve predictive capabilities for conditions where inner-electron bonding becomes important, strong coupling and degeneracy emerge, and quantum effects induce structural or electronic complexities; and (2) to advance the understanding of physical processes at the confluence of multiple energy scales, and those associated with chemical bonding, atomic, and hydrodynamic phenomena.

By engaging theory, computation, and experiments, LLE provides experimentally benchmarked equation-of-state, conductivity, and transport models that are transforming simulation accuracy and advancing our understanding of planetary science, inertial fusion energy, and stockpile stewardship science.

Computational Quantum High-Energy-Density Science

At LLE, we are advancing the discovery of new physics in quantum high-energy-density (HED) matter and developing reliable physics models for multi-physics codes that simulate inertial confinement fusion (ICF) and HED experiments. Our research combines theoretical modeling with high-performance computational simulations based on first-principles quantum mechanical methods, including density-functional theory (DFT), time-dependent density-functional theory (TD-DFT), path-integral Monte Carlo (PIMC), and path-integral molecular dynamics (PIMD). These efforts are driven by LLE scientists who are expanding computational capabilities across multiple fronts—from creating finite-element-based DFT codes like MELIORA to developing the next-generation opacity code, ROCSTAR, designed to accurately model radiation transport in HED materials.

At LLE, leading scientists are closely working with PhD students side-by-side to push the envelope for better understanding properties of materials under extreme HED conditions. These rigorous trainings in theoretical/computational quantum HED science have better prepared next-generation stewards for DOE/NNSA missions in stockpile stewardship and national security.