Ultrapowerful bursts of energy could some day help control fusion reactions

Utilizing energy explosions that last a couple zeptoseconds, scientists may theoretically be able to look inside an atom and control nuclear fusion. A zeptosecond (10^-21 seconds) is a term officially adopted in 1991 by CGPM, the primary intergovernmental treaty organization responsible for the International System of Units(SI) system.

Alexander Kaplan of Johns Hopkins University in Baltimore states, "I'm not talking about exciting or suppressing atomic explosions yet. But his could possibly mean we could touch the nucleus, and one of the ultimate ideas would be trying to control nuclear reactions, slow them down or the other way around."

Incredibly powerful magnetic fields are used to create energy bursts with an intense enormity that can be found in collapsed stars. Eventually, scientists may be able to use these potent energy eruptions to accomplish anything from scanning the human body to generating experimental states of matter for further investigation of the origin of the universe.

Laser expert Mike Perry, director of the photonics division at General Atomics in San Diego, comments, "Zeptosecond pulses and astrophysical scale magnetic fields would be a significant achievement. Any ability to perform astrophysical scale experiments in the laboratory offers the promise to test rapidly unfolding theories of the early universe."

Kaplan and his colleague Peter Shkolnikov of the State University of New York in Stonybook proposed the use of a "lasetron" in the scientific journal Physical Review Letters. A lasetron, an extremely powerful laser-driven electron accelerator, can in theory generate pulses and fields.

Hypothetically, a lasetron needs a petawatt (10^15 watt) laser to deliver laser beams of quadrillion-watt pulses in less than a trillionth of a second, which exceeds the entire U.S. electrical generating capacity by 1,200 times. The petawatt laser is fired at wires with a few hundred atoms in diameter can potentially drive electrons into targets at near-light speed. Since kinetic energy transforms into mass at "ultra-relativistic" speeds, the electrons in motion are about 100 times more massive than electrons at rest. Picture forceful hammers hitting tiny anvils; the tremendous energy and speed of the electrons concentrate at the target.

One of the three petawatt lasers being created around the world is currently at the Lawrence Livermore National Laboratory in California under Perry's management. Kaplan and Shkolnikov propose the theory that a circularly polarized petawatt laser beam (where light rays are aligned to move circularly) would set electrons into motion around an extremely tight orbit of about 3,000 angstroms in diameter (3,000 times the diameter of a hydrogen atom). A rotating electrical charge in such confined conditions would create a magnetic field of about one million tesla, which is more overwhelmingly powerful than any made on this planet thus far.

Kaplan explains, "It's unbelievable. The best we can get in the lab nowadays is a few hundred tesla, maybe 1,000 if we were generous with fields developed by explosions. This is a magnetic field more powerful than any that normally exists in the sun, and closer to the field found in a white dwarf."

The million-tesla field is potent enough for the electrons to merge into a giant electron; this massive electron fires giant energy bursts. The greater the speed of the electrons, the quicker the pulse, which means that the energy bursts theoretically lasts only zeptoseconds. The potential usefulness and development of this possibility is enormous. Light can travel around the globe in one tenth of a second, but light can only travel the distance of an atomic nucleus in a zeptosecond.

Kaplan hopes that zeptoseconds will allow scientists to look inside a nucleus, "see almost a movie, look at internal nuclear motion or a fast process like fusion or fission, or stimulate and control nuclear reactions. It is possible to start doing crazy things."

Unfortunately, the experimental application still remains far behind the idea. Kaplan also mentioned that no sensor is yet sensitive enough to detect zeptosecond pulses, and a million-tesla field would blow out any detectors so far. The practical control of the amount of energy associated with the new theory is still an obstacle.

Perry added, "The edges of a petawatt pulse would explosively vaporize its target before the pulse's core drives the wire's electrons to near-light speeds."

Nonetheless, Kaplan proclaimed, "Weaker lasers could still generate powerful fields for advanced magnetic scanners in an X-ray emulating system that would allow you to look into people at an airport, for example. It's one of those wild shots that produce a whole chain of ideas.