With the advent of the current generation of high-power lasers, a high-energy-density environment can be routinely reproduced in a laboratory. Energy densities in excess of 1012 ergs/cm3 exist in the core of stars, and, until recently, they could be reproduced only through nuclear explosions. The US ban on nuclear testing closed the access to such high-energy densities until high-power lasers such as NOVA at the Lawrence Livermore National Laboratory and OMEGA at the University of Rochester’s Laboratory for Laser Energetics became available. Energy densities of 1012 ergs/cm3 correspond to a pressure of 1 Mbar. For example, a milligram of hydrogen at a temperature of 1 keV confined within 1 cm3 is at 1 Mbar of pressure. At such high temperatures, matter is in the form of plasma, where atoms decompose into electrons and ions. With the construction of the next generation of high-power lasers-the National Ignition Facility at LLNL and the Laser Megajoule project (LMJ) in France-pressures in the range of 10 Gbars are expected to be routinely achieved and energy densities never obtained before will be accessible.
The access to the gigabar regimes and the achievement of controlled thermonuclear ignition still present many challenges. Thermonuclear ignition is the process of self-sustained burn occurring in the thermonuclear fuel of hydrogen bombs and in the core of the sun. Achieving ignition in a laboratory has been the “dream” of many generations of scientists. With the advent of the next generation of super lasers, controlled thermonuclear ignition seems to be within our reach for the first time in history. Ignition will be attained by inertial confinement (ICF) of a hot, dense plasma compressed by the super lasers over an interval of a few nanoseconds.
High-energy-density physics encompasses all the physics issues pertinent to the production, characterization, and utilization of plasmas in such a high-pressure environment. The achievement of high-energy-density regimes and thermonuclear ignition can be accomplished only through extensive studies of laser-plasma interaction, radiative hydrodynamics, plasma physics, atomic physics, and nonlinear optics. So far, the main applications of high-energy-density physics are laboratory simulations of astrophysical phenomena (supernova explosions, astronomical jets, equation of state), science-based nuclear stockpile stewardship, and fusion energy productions via inertial confinement fusion.
The University of Rochester offers Ph.D. programs for physics and engineering majors with concentration in high-energy-density physics, plasma physics, and inertial confinement fusion studies. Applications can be submitted to either the Department of Mechanical Engineering or the Department of Physics & Astronomy. Graduate courses are taught by faculty, most of whom hold joint appointments in these departments, and all of whom are active in research at LLE. Most of the courses are crossed-listed in both departments. In addition, there is close cooperation between the high-energy-density plasma group in the Astrophysics section of the Physics Dept., LLE, and ME.