Closer NNSA–Academic Links Needed to Boost Plasma Physics, NRC Says

The growing sophistication of instruments for observing matter under extreme high-energy-density (HED) conditions in both astrophysics research and laboratory plasmas has created an “opportune time” for scientists to “develop a fundamental understanding of the physics of high energy density plasmas.” That is the bottom-line conclusion of a new report, Frontiers in High Energy Density Physics, by the National Research Council’s committee on HED plasma physics.

Key to achieving significant advances in HED physics is recognizing the interconnectedness between laboratory research and astrophysical research, said Ronald Davidson, a Princeton University plasma physicist and chair of the committee that produced the report. Davidson pointed to a section of the report that says HED physics “spans a wide range of physics areas, including plasma physics, laser and particle beam physics, materials science and condensed matter physics, nuclear physics, atomic and molecular physics, fluid dynamics and magnetohydrodynamics, and astrophysics.” The intellectual challenge of HED physics “lies in the complexity and nonlinearity of the collective interaction process that connect all of these subfields of physics,” the report says. Because of the complexity of the science that is the subject of the report, Davidson and his committee colleagues open the document with a lengthy definition of HED physics. “Recent advances in extending the energy, power, and brightness of lasers, particle beams, and Z-pinch generators make it possible to create matter with extremely high energy density in the laboratory,” the report begins. “The collective interaction of this matter with itself, particle beams and radiation fields is a rich, expanding field of physics.” The working definition of HED “refers to energy densities exceeding 10¹¹ joules per cubic meter (J/m³), or equivalently, pressures exceeding 1 megabar (Mbar).”

Because much of the federal funding of HED physics is related to nuclear weapons research and stockpile stewardship, the report makes several recommendations that focus on National Nuclear Security Administration research programs. The report’s first recommendation calls on the NNSA to “continue to strengthen its support for external user experiments on its major high energy density facilities.”

The three major HED facilities in the US are the OMEGA laser system at the University of Rochester in New York; the Z machine x-ray generator at Sandia National Laboratories in New Mexico; and the ATLAS pulsed-power facility at Los Alamos National Laboratory, also in New Mexico. The National Ignition Facility, when completed, will be the highest-power HED laboratory. NIF is being constructed at Lawrence Livermore National Laboratory as the key test facility for the NNSA’s nuclear weapons stockpile stewardship program. (See Physics Today, January 2001, page 21 .)

The report also recommends that the NNSA expand its stewardship science academic alliances program, which funds about $12 million in HED-related research projects at universities. “The NNSA doesn’t have a history of funding university research,” Davidson said. “The NNSA mainly supports research at the weapons laboratories. But they have initiated the academic alliances program and it is very much needed and appreciated. What has been done is an important first step, but only a first step.”

The report also calls for a “significant effort” to be made by the federal government and the university community to expand the involvement of NSF, NASA, the US Department of Defense, and the nondefense directorates of the Department of Energy in funding HED physics. That recommendation, and one calling for more federal support at smaller, “university-scale” HED facilities, is intended in part to attract new students and researchers to the field.

In addition to recommending upgraded instruments at some HED facilities, the report calls for more support for an “iterative computational-experimental integration procedure” for HED physics research, and stronger federal interagency cooperation so that federal funding isn’t constrained by the weapons orientation of many of the NNSA’s programs.

“We didn’t tally up specifically the support that exists [for HED physics], but we were struck by the opportunity for agencies to work together to actually fund frontier science,” Davidson said.

The report makes for challenging reading for nonscientists in Washington, DC, but Davidson is scheduling briefings with officials at the relevant federal offices, including the DOE’s Office of Science and the Bush administration’s Office of Science and Technology Policy.