Seeking an Infinite Energy Source through Nuclear Fusion
University of Rochester
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Professor Robert L. McCrory calls it "bringing star power to Earth"—re-creating on our planet the nuclear reactions that power the Sun, and thereby securing an inexhaustible source of energy that emits no greenhouse gases, requires no environmentallydestructive mining or drilling, and relies on fuel as abundant as seawater. This is the vision of the University of Rochester's Laboratory for Laser Energetics (LLE), which is committed to making the dream of producing electricity from nuclear fusion, which makes the Sun shine, a reality.
Hydrogen bombs also get their energy from the fusion of atomic nuclei, of course, but for nuclear fusion to generate energy that can be tapped for electricity the reaction must scaled down more than a million times in energy. The LLE therefore investigates inertial confinement fusion, which explores the behavior of matter under conditions of extremely high energy density and temperature. In inertial confinement fusion, ultra-high power lasers emitting hundreds of terawatts of power (1 terawatt equals 1 trillion watts, and is comparable to the power produced by 1,000 electric power plants) irradiate a capsule containing the heavy hydrogen isotopes, deuterium and tritium. The laser energy compresses and heats the hydrogen to conditions near those at the center of the Sun, causing it to undergo fusion. The result is helium fuel and other energetic particles.
If the compressed mass is large enough, the highpressure, high-temperature conditions last long enough to produce more energy than is used to power the laser, allowing inertial confinement fusion to be used to produce electric power. The field has made significant strides since it began in the early 1970s and is now within 10 years of demonstrating its scientific feasibility.
The LLE is the country's only large-scale facility for inertial confinement fusion at a university rather than a weapons lab. Its showcase facility is the 60-beam OMEGA laser, which can deliver more than 30 billion times the instantaneous power of sunlight that falls on one square meter of the Earth's surface, but concentrates it all on a target less than 1 millimeter across.
"The LLE aims to bring star power to Earth."
Inertial confinement fusion research has potential applications in other important areas of science and technology. The most immediate is in nuclear weapons security. By simulating the extreme temperatures and pressure of a thermonuclear burn, inertial confinement fusion can be used to, for instance, predict how nuclear warheads in the nation's stockpile degrade as they age; as a result, much of the LLE's research is funded by the Department of Energy's National Nuclear Security Administration. Research on inertial confinement fusion at the LLE has also opened up new areas of basic research ranging from laboratory astrophysics (simulating the nuclear reactions inside stars) to the investigation of the behavior of matter under ultra-high dynamic stress.
Rochester and its surrounding area has long been a technologically sophisticated region with significant resources in optics, physics, materials science, chemistry, nuclear physics, plasma physics, photonics, and laser technology. When the late Professor Moshe Lubin began the work that would lead to the official founding of the LLE in 1970, he started with lasers abandoned by the Eastman Kodak Company, another Rochester-based institution. The University of Rochester, too, has long had strong programs in optics, photonics, and physics.
The importance of the LLE in advancing inertial confinement fusion for energy production as well as national security and basic research is reflected in the breadth of its support. The lab, directed by McCrory since 1983, receives funding from the National Nuclear Security Administration and the New York State Energy Research Development Authority.
The next decade promises a number of historic milestones. The LLE is on track to demonstrate inertial confinement fusion ignition and burn, showing the way toward long-term applications of this approach to energy production. The OMEGA laser, by producing ultra-high-density states of matter, promises to solve many outstanding puzzles in materials science, fundamental atomic physics, fundamental nuclear science, and plasma physics.
And although they do not have the sex appeal of the lasers themselves, the ultra-high speed and high-precision instrumentation required to measure the conditions in the targets probed by the lasers promise to generate revolutionary technologies in their own right. The LLE is also expected to inspire the development of advanced numerical models that, running on tomorrow's high-speed computers, will be able to aid in the design and modeling of future experiments—think of it as virtual nuclear fusion. In addition, the central role that the OMEGA laser plays in the LLE is expected to lead to the development of ever-more powerful high-efficiency descendants.
The LLE continues to be one of the leading energy research facilities in the world. Attracting as many as 300 scientists each year from laboratories, universities, and companies across the country and the world to carry out advanced research in highenergy/high-density physics and inertial confinement fusion, it is a significant source of innovation and talent (almost 1,000 individuals are currently involved in the program). As a result, the LLE has been a key economic driver for the Finger Lakes region, where LLE technology has served as the foundation for such area companies as QED Technologies, Inc., Sydor Instruments LLC, and Lucid, Inc.
Photo: LLE researchers work on an OMEGA laser.