An international team of scientists working at General Atomics' research facility in La Jolla has made a "significant" technological advance in the search for a reactor vessel that can withstand the tremendous heat needed to harness fusion energy.
In an experiment that researchers replicated more than a dozen times during May, General Atomics' fusion research laboratory doubled the previously achievable temperature with the same amount of power previously used, said General Atomics Vice President David Overskei.
"This is the state of the art today," Overskei said. "It's been nine years since anything this major has occurred."
Scientists have been striving to create energy through fusion--the use of intense heat to fuse atoms and create energy--as opposed to fission, in which atoms are split to create power.
Sustained nuclear fusion has long been an elusive dream of physicists. Scientists continue to be stymied in their quest because of the tremendous amounts of energy needed to produce the intense heat needed for a fusion reaction.
Reactor vessels deteriorate in the face of the tremendous heat, and scientists also are searching for ways to reduce the tremendous amounts of energy needed to create fusion.
Although scientists can use magnetic fields to help contain hot gases, or plasma, inside a reactor, the reactor vessel's walls quickly deteriorate because of the superheated temperatures produced in the quest for fusion.
General Atomics used diborane gas to coat the inside walls of its research reactor with a microscopically thin layer of boron. That boron film "keeps the wall from (deteriorating) and getting inside the high-temperature plasma," Overskei said.
Scientists working at a fusion research center in Julich, Germany, developed the method of coating vessel interiors with boron. But the technique brought only modest advances when conducted with the German test reactor, Overskei said. What Overskei called the "dramatic" advance at General Atomics' laboratory was made possible by "certain engineering features" of General Atomics' vessel, Overskei said.
Overskei compared the research vessel used in the experiment to "a one-cylinder engine" that might one day be used as the basis for a more-powerful eight-cylinder engine. The result means that the high temperatures needed to produce fusion with significantly less power or hardware may be attained, Overskei said.
"Some of the surface of the vessels always makes its way into the plasma, which makes the plasma deteriorate," Overskei said. "The boron kept the surface from getting back into the plasma."
Jorg Winter, a German scientist who earlier had experimented with the boron layer in Germany, has been experimenting with the boron deposition technology alongside General Atomics researchers for six months.
"While they were doing experiments in Germany for a couple of years . . . they had never seen anything as dramatic as we did," Overskei said.
During General Atomics' initial experiment, "nothing seemed to happen, and at the time we thought that we had not done it quite right," Overskei said. During subsequent experiments "we got fantastic results that were reproducible," Overskei said.
In addition to performing fusion research, General Atomics is playing a key role in an effort to lure an international fusion engineering research project to San Diego. The U.S. Department of Energy in January proposed that the project be built in San Diego. However, the international consortium that will build the International Thermonuclear Experimental Reactor has yet to determine if it will be built in San Diego, Japan or Europe.
The recent advance at General Atomics won't directly help the city in its attempt to win the ITER, Overskei said. However, the advance will enhance San Diego's reputation as a center for fusion research, Overskei said.
The U.S.-German team reported the advance in a paper delivered June 7 at the European Physical Society meeting in Berlin.