Berkeley Lab

Fusion Science and NDCX-II

Our division has long been involved in the quest for inertial fusion energy (IFE) as a future power source, primarily through R&D on heavy-ion induction accelerators, an approach pioneered here. Today our program collaborates closely with Lawrence Livermore National Laboratory and the Princeton Plasma Physics Laboratory on topics relevant to inertial fusion driven by beams of heavy ions.The latest of the experimental facilities we built along the way is an accelerator called the Neutralized Drift Compression Experiment II. It proved to be a natural match for some key problems in the emergent science of high-energy-density physics with laboratory plasmas.Basic R&D toward the development of advanced materials that will be needed for the future of fusion energy, where they must withstand 14.1 MeV neutrons that are more damaging than neutrons from fission reactors, is also a promising application of NDCX-II.Now part of the Ion Beam Technology Program, our work in fusion energy sciences has focused increasingly on this new facility, where beamtime is available to outside researchers interested in HEDP.

NDCX-II: A Unique Capability for HEDP Research

With the support of the American Recovery and Reinvestment Act, we built an accelerator called the Neutralized Drift Compression Experiment II, and began using this machine (and, alongside it, NDCX-I) for HEDP experiments. Since mid-2014 we have been using renewed funding from the DOE Office of Fusion Energy to build out NDCX-II to its full potential. When the build-out phase is complete, NDCX-II will deliver intense, short pulses of ion beams with a kinetic energy of 1.2 MeV. The emergent science of high-energy-density physics with laboratory plasmas, a topic closely related to IFE target physics, has come to play a large role in our program. Some key aspects of HEDP—dubbed “the X Games of contemporary science” by a National Research Council committee—are a natural match for the experimental facilities, modeling techniques, and areas of expertise of our program and its collaborators.

When the present build-out phase is complete, NDCX-II will deliver intense, short pulses of ion beams with a kinetic energy as high as 1.2 MeV. With focusing and drift compression—beam manipulations that we studied extensively for fusion-energy purposes— this will enable uniform heating of 2-micron-thick targets to a temperature of one electron-volt. While the achievable target temperature at NDCX-II is much lower than what can be achieved with intense laser pulses, the excited volume is relatively large and uniformly heated, which enables precision diagnostics of the transient warm-dense-matter state.

The high degree of tunability and control in ion species (e.g., He, Li, K, Cs), kinetic energy (0.1 to 1.2 MeV), spot size (from less than 1 to as high as 10 mm2, and pulse length from less than 1 to over 600 nanoseconds) allows us to tune excitation conditions across three physical regimes: from isolated collision cascades, through the onset of order-disorder phase transitions, to warm-dense-matter states.

NDCX-II and Materials Science for Fusion Energy

Fusion energy, whether inertially or magnetically confined, has long been attractive for its environmental sustainability and the near unlimited supply of “fuel.” It can however be rough on equipment. Most of the energy comes out in the form of neutrons, moving much faster than those from a fission reactor. Materials that can withstand them, and/or become less radioactivated, will be needed.

NDCX-II enables systematic pump-probe study of the dynamics of radiation-induced defects of fusion materials. Compared to other means of performing this basic research, NDCX-II is attractive because of its high repetition rate (two pulses per minute) and short ion pulses, as well as by the direct way in which ions interact with the material being tested.

Understanding the multi-scale time evolution of radiation damage, from picoseconds to seconds, is of fundamental importance for our understanding of radiation effects in natural processes. It can aid the development of advanced materials for use in any high radiation environments (including not only fusion materials but also fission reactor components and also space electronics). Our goal is first-in-class in- situ data on short time scales to experimentally benchmark simulation tools that are widely used to predict the evolution of radiation damage in materials.

Pushing the capability to control very intense, space-charge-limited ion beams will also help lay the foundation for inertial-fusion-energy drivers and, generally, inform the development of ion beam technologies at the intensity limits. This will be useful for a wide range of applications in high energy physics, medicine, materials processing and national security.

To Learn More…

NDCX-II and its uses are the subjects of “A New Accelerator to Study Steps on the Path to Fusion”, a feature article by Berkeley Lab’s public information department.

For more information on the uses of NDCX-II, see this article, circa the beginning of the project.

Recent Publications

  • Fusion Science and Ion Beam Technology - Fusion Science and NDCX-II R.O. Bangerter, A. Faltens and P.A. Seidl, “Accelerators for inertial fusion energy production,” Reviews of Accelerator Science and Technology 6 (2013), pp. 85–116. Hua Guo, Arun Persaud, Steve Lidia, Andrew M. Minor, P. Hosemann, Peter A. Seidl, and Thomas Schenkel, “Dynamic investigation of defects induced by short, high current pulses of […]


Background Brief: The Why and How of Inertial Fusion Energy

Artist’s conception of an inertial fusion power plant
As the world contemplates dwindling fossil-fuel supplies and the environmental costs of energy production, fusion looks ever more appealing. The fuel (hydrogen isotopes called deuterium and tritium) can be readily obtained, and the reactions do not create the large long-lived radioactive waste stream associated with fission. However, controlled fusion on a power-plant scale will require years of further development; typical estimates call for a demonstration power plant to begin operation in two or three decades.The DOE supports two approaches to controlled fusion. One is called magnetic fusion energy and is based on a large, continually reacting plasma confined by “magnetic bottles” such as tokamaks. The other approach is inertial confinement, in which a small capsule of fusion fuel is heated and compressed, so that the fusion reaction take place before the fuel has a chance to overcome its own inertia and apart. A large program, supported by the DOE’s National Nuclear Security Agency, is studying the basic physics of the inertial approach, using powerful lasers to drive this reaction.

Inertial Fusion Research at Berkeley Lab

LBNL’s Fusion Energy program is part of a smaller parallel effort, supported by the DOE’s Office of Science, to harness inertial fusion energy for electric power production by using powerful and energetic beams of heavy ions to drive the target The long-term goal is for the targets to yield much more energy than was put into them by the beams. Our program has the long-range goal of developing suitable heavy-ion accelerators that will not only “drive” a fusion target, but do so with a cost, efficiency, and reliability that make business sense as the basis for a power plant.

Since our beginnings in 1982, we have been progressively scaling up induction accelerator systems that transport beams, give them more energy, and focus and compress the pulses so as to impart the most energy to the target as quickly as possible. This is the context in which NDCX-II came into being.

We are part of the Ion Beam Technology Program in ATAP Division.

For further information, here is a detailed inertial-fusion-energy tutorial.