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Rochester, NY, United States

Dennis Whyte, professor of nuclear science and engineering, began pursuing fusion energy research at MIT in 2006, attracted in large part by the opportunity to work at the Plasma Science and Fusion Center (PSFC). He says it’s “a special place, with a compelling combination of being at the forefront of an important research area like fusion, while being rooted strongly in education.” As 2015 begins, Whyte is assuming leadership of the PSFC from 20-year veteran professor of physics Miklos Porkolab, who is returning to teaching and research. Whyte plans to steer the center into an era of smaller, faster, and more modular experimentation while maintaining the center’s educational excellence. Whyte refers to his assignment as “humbling,” but expresses confidence in the “really amazing” PSFC team and its ability “to build an even more cohesive case for fusion energy going forward.” His extensive Department of Nuclear Science and Engineering (NSE)/PSFC research contributions include studies of magnetic energy confinement techniques that were honored with the International Atomic Energy Agency’s 2013 Nuclear Fusion Journal Prize. Founded in 1976, the PSFC has about 200 affiliated faculty members, students, researchers, and technicians from units spanning the Institute, including the departments of Physics, Materials Science and Engineering, and Electrical Engineering and Computer Science, as well as NSE. Also on site are several dozen domestic and international collaborators. While relatively large for a university program, the center is small by global fusion-research standards. “We have impact way above our size,” says Whyte. “By any measure we’ve been extremely successful at creating key breakthroughs across broad areas of fusion — magnetic and inertial confinement, diagnostics, plasma-materials interactions, and superconducting magnet technologies. We plan to continue contributing, while ensuring that education of the next generation of scientists is completely integrated into everything we do.” Much of PSFC’s work has leveraged the high-field Alcator C-Mod tokamak fusion reactor, one of just three major tokamak facilities in the U.S. But Whyte says today’s budgetary realities and the changing nature of fusion development require a new strategy. Whyte’s top near-term priority is evaluation of options that will enable “MIT-quality” experimentation at the scientific frontier, while keeping the center’s research staff intact and cohesive. One possible example is the Advanced Divertor Experiment (ADX), a facility that would use “a small, purpose-built experiment to address key challenges in the boundary-plasma interface with materials, and controlling and sustaining electric current in plasmas. That’s what MIT should be doing, and the educational mission is built right in,” he explains. In addition, work in related fields like basic plasma-materials interactions, nuclear detection, and advanced diagnostics will also be nourished, in support of other NSE and Institute-wide efforts, including nuclear security. Indeed, extending and expanding PSFC’s ties to MIT academics is another priority. “Tying into the breadth of activities at MIT helps makes PSFC unique,” says Whyte. “Nurturing our faculty and our academic roots is part of how we’ll continue to attract the best and brightest students.” Looking beyond the Institute, Whyte sees opportunities for continued integration with national and international fusion efforts. He cites PSFC senior scientist Richard Petrasso’s group as a model — “they’ve developed capabilities to make unique measurements for the National Ignition Facility, and the University of Rochester’s Laboratory for Laser Energetics, two of the largest laser/inertial fusion experiments. There’s heavy student involvement, and they’re a vital part of those national teams.” Whyte acknowledges that the international ITER fusion reactor project in France is facing challenges, but said the PSFC — a key contributor to date — will continue its support. Simultaneously, he notes, the nimbler experimental approach could enable fusion development on smaller devices like the PSFC’s conceptual ARC reactor. It leverages new high-temperature, high-field superconducting magnet technology and could produce as much power as ITER’s reactor in just one-tenth the volume. “Smaller and sooner is my mantra,” says Whyte. Disruptive technologies, like the ARC’s superconducting magnets, could create “an extremely exciting pathway that can make fusion happen sooner, while also informing what we do in the near term. We’re advocating for that, and for applying an integrated, multi-disciplinary view of fusion, importantly including nuclear engineering perspectives, to near-term plasma research. “We should study the parameter space required for magnetic fusion energy: high-plasma pressure, high-power density, and steady-state. The compact high-field Alcator experiments, and a focused experiment like ADX, show that this approach can be highly effective for advancing fusion science at small size,” he concludes. While the PSFC will be a different place in five or 10 years, Whyte is confident that its special combination of impactful leading-edge research, international collaboration, and strong student involvement will thrive and evolve.

Pollock B.B.,Lawrence Livermore National Laboratory | Pollock B.B.,University of California at San Diego | Clayton C.E.,University of California at Los Angeles | Ralph J.E.,Lawrence Livermore National Laboratory | And 18 more authors.
Physical Review Letters | Year: 2011

Laser wakefield acceleration of electrons holds great promise for producing ultracompact stages of GeV scale, high-quality electron beams for applications such as x-ray free electron lasers and high-energy colliders. Ultrahigh intensity laser pulses can be self-guided by relativistic plasma waves (the wake) over tens of vacuum diffraction lengths, to give >1GeV energy in centimeter-scale low density plasmas using ionization-induced injection to inject charge into the wake even at low densities. By restricting electron injection to a distinct short region, the injector stage, energetic electron beams (of the order of 100MeV) with a relatively large energy spread are generated. Some of these electrons are then further accelerated by a second, longer accelerator stage, which increases their energy to ∼0.5GeV while reducing the relative energy spread to <5% FWHM. © 2011 American Physical Society.

Quillen A.C.,University of Rochester | Giannella D.,University of Rochester | Shaw J.G.,Laboratory for Laser Energetics | Ebinger C.,University of Rochester
Icarus | Year: 2016

Close tidal encounters among large planetesimals and Moons should have been more common than grazing or normal impacts. Using a mass spring model within an N-body simulation, we simulate the deformation of the surface of an elastic spherical body caused by a close parabolic tidal encounter with a body that has similar mass as that of the primary body. Such an encounter can induce sufficient stress on the surface to cause brittle failure of an icy crust and simulated fractures can extend a large fraction of the radius of body. Strong tidal encounters may be responsible for the formation of long graben complexes and chasmata in ancient terrain of icy Moons such as Dione, Tethys, Ariel and Charon. © 2016.

U.S. Naval Research Laboratory (NRL) plasma physicist, Dr. Alexander L. Velikovich, receives the 2015 IEEE Plasma Science and Applications Award for advancing the theory of plasma shocks and hydrodynamics and magneto-hydrodynamics — enabling many-fold increases in both Z-pinch and laser-plasma experimental performance in radiation and fusion applications. Presented by the Nuclear and Plasma Sciences Society (NPSS), the award recognizes outstanding contributions to the field of plasma science and engineering to include plasma dynamics, thermonuclear fusion, plasma sources, relativistic electron beams, laser plasma interactions, diagnostics and solid-state plasmas. Author and co-author of more than 170 publications, with over 2,500 citations, Velikovich developed the first analytical theory to calculate the time-dependent growth of compressible Richtmyer-Meshkov (RM) instability in the linear regime, as well as, non-linear RM theory explaining reduction of its growth rate for large initial amplitude. Most recently Velikovich developed a theory explaining the effect of shock-generated turbulence — discovered in numerical simulations at NRL over a decade ago — on the Rankine-Hugoniot jump conditions. Derived from the laws of mass, momentum and energy, many physical effects, first observed on the Nike krypton fluoride (KrF) laser at NRL, were recreated on both the Nova laser at the Lawrence Livermore National Laboratory, California, and the Omega laser at the Laboratory for Laser Energetics (LLE) located in New York. Velikovich's research on High Energy Density Physics (HEDP) and Inertial Confinement Fusion (ICF), particularly laser-fusion and Z-pinch-related plasma hydrodynamics, formed the theoretical basis for x-ray generation in Z-pinch plasma radiation. Modeling and interpretation of these results were instrumental in establishing the physical picture of the Rayleigh-Taylor (RT) instability seeding in laser fusion targets caused by the roughness of the front and rear surface of a laser target. Research that later translated into the development of a theory that provided the physical basis for most hydrodynamic experiments performed on the Nike laser over the past decade. Earning a Master of Science equivalent degree in physics from Moscow State University Department of Physics, Moscow, Russia, in 1974, Velikovich completed a Ph.D. equivalent degree in plasma physics and chemistry awarded by Kapitza Institute for Physical Problems, U.S.S.R. Academy of Sciences in 1978. In 1991 he earned an Advanced Degree of Doctor of Science (equivalent of Habilitation in European Union countries) in Electrophysics awarded by High Current Electronics Institute, Russian Academy of Sciences, Tomsk, Russia. Velikovich started at NRL in 1993 as a contractor, transitioning to federal civil service at NRL in 1999. In 2005 Velikovich was elected Fellow of the American Physical Society upon the recommendation of its Division of Plasma Physics for "outstanding contributions to the theories of dynamics and stability of Z-pinch plasmas, Richtmyer-Meshkov instability and related effects of early-time perturbation seeding and evolution in laser plasma targets." In 2010, along with colleagues from Sandia and NRL, Velikovich shared the 2010 Department of Energy (DoE) Defense Programs Award of Excellence for "increased cold x-ray source yields, improved source characterization and debris mitigation techniques to qualify stockpile components on refurbished Z machine." In 2000, 2007, 2010, and 2012, he was the recipient of the NRL Alan Berman Research Publication Award. In 2015 he received the NRL Sigma Xi award for Pure Science. About the U.S. Naval Research Laboratory The U.S. Naval Research Laboratory provides the advanced scientific capabilities required to bolster our country's position of global naval leadership. The Laboratory, with a total complement of approximately 2,500 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 90 years and continues to advance research further than you can imagine. For more information, visit the NRL website or join the conversation on Twitter, Facebook, and YouTube.

Robey H.F.,Lawrence Livermore National Laboratory | Boehly T.R.,Laboratory for Laser Energetics | Olson R.E.,Sandia National Laboratories | Nikroo A.,General Atomics | And 3 more authors.
Physics of Plasmas | Year: 2010

Capsule implosions on the National Ignition Facility (NIF) [Lindl, Phys. Plasmas 11, 339 (2004)] will be driven with a carefully tailored sequence of four shock waves that must be timed to very high precision in order to keep the fuel on a low adiabat. The Hohlraum conditions present during the first three shocks allow for a very accurate and direct diagnosis of the strength and timing of each individual shock by velocity interferometry. Experimental validation of this diagnostic technique on the OMEGA Laser Facility [Boehly, Opt. Commun. 133, 495 (1997)] has been reported in [Boehly, Phys. Plasmas 16, 056302 (2009)]. The Hohlraum environment present during the launch and propagation of the final shock, by contrast, is much more severe and will not permit diagnosis by the same technique. A new, closely related technique has been proposed for measuring and tuning the strength and timing of the fourth shock. Experiments to test this technique under NIF-relevant conditions have also been performed on OMEGA. The result of these experiments and a comparison to numerical simulations is presented, validating this concept. © 2010 American Institute of Physics.

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