LBNL: AFRD: Heavy Ion Fusion VNL

Fusion Energy Research and Ion Beam Technology

We further inertial fusion energy as a future power source, primarily through R&D on heavy-ion induction accelerators. Our program is part of a "Virtual National Laboratory," headquartered in AFRD, that joins us with Lawrence Livermore National Laboratory and the Princeton Plasma Physics Laboratory in close collaboration on inertial fusion driven by beams of heavy ions. The closely related emergent science of high-energy-density physics (HEDP) has become a major additional focus.

For further synergy, we have combined forces with the former Ion Beam Technology Program. Their achievements from 2006 until this May 1, 2007 reorganization are reported in their own chapter.

Contact: HIF-VNL director Grant Logan. The VNL has written an introduction to heavy-ion-driven inertial fusion energy. For a more-technical look at we are doing, please visit the AFRD Fusion Energy Research Program website or read Heavy Ion Fusion News.

A picture of a
possible IFE powerplant, with a link to an article explaining why we need non-petroleum energy sources and what is potentially so good about fusion

Background and Context

The Department of Energy supports two major fusion research programs, one based on magnetic confinement, the other on inertial confinement. The most promising form of inertial confinement fusion for energy production uses beams of heavy ions to heat and compress, or “drive,” a target that contains deuterium and tritium. These isotopes of hydrogen fuse together, giving off a burst of energy that is captured and converted into heat in the target chamber. A beam power of 4 megajoules could generate a fusion yield of about 200 megajoules. Ultimately, as experiments segue into a pilot powerplant (typical estimates call for a demonstration power plant around 2035),repeating this process several times a second will keep the energy-absorbing part of the target chamber at a steady high temperature so that a heat exchanger can produce steam for turbines.

Accelerators producing intense beams of heavy ions are also useful tools for uniformly heating matter for research in high-energy-density physics (HEDP). They can enable the study of strongly-coupled plasma physics in the warm dense matter regime in the near term. With further development, they can also open up the study of other HEDP regimes, including the hydrodynamics of heavy-ion-driven, direct-drive targets relevant to heavy-ion fusion. All of this requires us to understand the fundamental beam physics issues that limit the compression of ion beams in both space and time en route to the target, as well as the collective beam-plasma interaction processes and beam energy deposition profiles within the dense plasma targets.

Progress Update

We look forward to providing beams in 2008 that enable meaningful user experiments in the warm dense matter (WDM) aspects of HEDP. In 2006 through early 2007, our accomplishments included:

Improved compression of intense neutralized beams. We achieved as a much as seventyfold current amplification in the Neutralized Drift Compression Experiment (NDCX-I), a VNL facility at LBNL that uses a new ferroelectric plasma source. The year also saw the first simultaneous transverse and longitudinal beam compression in NDCX-I, resulting in compressed beam density increases that were consistent with simulations. Beam compression is important to both HEDP and eventual fusion applications because it means the beam power is deposited into the target in a shorter time, which amounts to hitting it harder.
First results on how electron clouds affect transport of high-current beams in solenoids. AFRD has a pioneering and leading role in the study of these potentially disruptive electron-cloud effects, which are now recognized as being very important in all kinds of intense beams, whether in high-energy and nuclear physics or in fusion and HEDP.
Simulations of next-step improvements in NDCX-I with a high-field final-focus solenoid. This powerful solenoid will be added this year, the goal being smaller focal spot sizes, which are needed for the first experiments on WDM next year.
Identification of a series of unique WDM experiments and associated scientific questions to be investigated beginning on NDXC-I next year.
Development and testing of new diagnostics for initial WDM target experiments in a new target chamber being constructed for NDCX-I.

HEDP: The “X Games” of Science

The new experiments, modeling tools, and accelerator development came in response to a mid-2004 request that we redirect the heavy ion fusion program towards near-term High Energy Density Physics (HEDP) research. The request came from the DOE Office of Science, the Office of Fusion Energy Science, and the White House Executive Office of Management and Budget. Some key aspects of this emergent field—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 the VNL.

Ion beams with the parameters we have been developing for HIF can be used to heat an HEDP target very evenly. This offers unique benefits for studying equations of state in “warm, dense matter.” Within five years, if funding is maintained, we will be able to heat targets to 1 eV. This will enable us to study the properties of warm dense matter—in particular, strongly-coupled plasmas at 0.01 to 0.1 times solid density, a frontier physics area within HEDP.

Pursuit of this five-year objective in HEDP has resulted in many innovations that will ultimately benefit heavy-ion fusion energy. These innovations include neutralized beam compression and focusing, which hold the promise of greatly improving the stage between accelerator and target chamber in a fusion power plant; and the PLIA, which may lead to compact, low-cost modular linear accelerators for use as fusion drivers.

The Road Ahead

Looking across a ten-year timeframe (the details of which are paced by funding), we are addressing three grand challenges.

Near Term: Understanding Compression: Over the next two or three years, we will gain a full understanding of the limits to compression (both transverse and longitudinal) of neutralized beams. Compression is important because it increases the power, or energy deposition rate, of the beams, and thus their effect on the target.
Integration at 1 eV: Within several years (perhaps 2008-9), we will integrate compression, acceleration and focusing into a single experiment, achieving enough power to bring targets to a temperature of one electron-volt: solidly in an area of frontier-physics interest for HEDP.
Building a User Facility From These Capabilities: Both of those achievements are mileposts en route to the third challenge will be to develop and integrate these capabilities to create a user facility for HEDP (with the goal of equation-of-state measurements good to within 5%). This facility must be affordable (<$50 million), offer a high shot rate (>10 Hz), and combine an accelerator, laser, and targets.

Learn More About...

Why fusion, and why now? Short answer: because we need a new energy source before the present ones run out. According to some projections, fusion will be on-stream just in the nick of time...
For additional technical details on our progress in both fusion and HEDP, where we plan to go in 2005 and 2006, and links to papers we published, download the Fusion Energy chapter of the 2006 AFRD Research Highlights in Portable Document Format.
The AFRD Fusion Energy Research Program has a website of its own, and communicates the latest developments in Heavy Ion Fusion News.
“Squeezing the Beams”describes a remarkable recent accomplishment by VNL researchers in beam compression—which increases the rate at which power is deposited into a target and thus is a key aspect of both HEDP experiments and IFE.
The U.S. Department of Energy, Office of Science, Office of Fusion Energy is the principal sponsor of our work.

Posted 27 June 2007 after review by B.G. Logan.
The administrative information for the AFRD website is applicable to this page.