Like a bolt of lightning, an electrical charge splits heavy hydrogen gas at the University of Maryland's energy research building in College Park. There is a purple flash and a loud snap like the cracking of a whip, then silence.
Physicist George goldenbaum grins.
Spheromak has done it again.
For a period of no more than 30 millionths of a second it has created a type of extremely hot gas, called plasma, that is similar to the material that constitutes the sun.
And science has advanced a tiny step closer to its elusive goal of creating "an artificial sun on earth," says Chuan Sheng Liu, acting director of the plasma and fusion energy studies program at College Park.
Spheromak, a machine that fires high-powered electrical charges through a glass cylinder containing heavy hydrogen isotopes, was invented last year by Goldenbaum and a group of other physicists at Maryland. Basically a device for measuring the movements of plasma particles, it is one of the newer and more advanced tools in the quest to design a nuclear reactor that will trigger the same type of nuclear fusion that occurs on the sun.
"It is the ultimate energy source," says Liu. "It will provide unlimited amounts of energy for future generations."
The opposite of nuclear fission, which is the breaking up of heavy uranium atoms, nuclear fusion is potentially much safer, and there are no radioactive wastes, the scientists say.
"A fusion reactor in fail-safe," says Liu, "because if anything goes wrong, the temperature will drop automatically and the fusion process will self-quench."
In the solar plasma, at temperatures up to 30 million degrees Fahrenheit, fusion occures when two light nucleii combine, or fuse, into a heavier one. When that happens a vast amount of energy is released.
This process can be duplicated in a laboratory by heating heavy isotopes of hydrogen, which can be extracted from sea water, to a plasma state in which pairs of the hydrogen nucleii fuse into the single nucleus of the gas helium, also releasing a powerful surge of energy.
For 30 years, says Liu, scientists and engineers the world over have been struggling to find ways to produce inexpensively in laboratories the kind of fusion that occurs naturally on the sun.
"It is the basic form of energy prevalent in the universe, and the supply is inexhaustible. One gallon of sea water has the potential for producing the energy equivalent of 30 gallons of gasoline."
The rub is that science has yet to find a way to produce fusion energy that does not require more energy to create than it produces.
That's where Spheromak comes in.
One of the major problems in plasma research is finding some way to contain the extremely hot plasma. Glass or metal containers won't do because the plasma would just melt the container.
Instead, scientist must create magnetic fields with which in contain the plasma, and the basic design for doing this is called Tokamak, a doughnut-shaped device with electrical coils running through the hole.
Electrical charges from the coils create the magnetic fields to contain the plasma, but the basic flaw with this concept is that the plasma tends to move about in unpredictable ways and neutrons in the plasma tend to hit the coils and damage them.
As an alternative, Goldenbaum and his colleagues at Maryland came up with a way to duplicate in the laboratory the types of plasma configurations that occur in astrophysical space. In those configurations, the magnetic fields are contained within the plasma itself.
What Goldenbaum designed was a glass cylinder with electrical coils wrapped around the outside to generate the magnetic field. Ring-shaped metal parts are attatched at either end of the cylinder. When high voltage is applied to the metal, a bolt of electricity shoots through the cylinder from one metal ring to the other.
The process heats the heavy hydrogen gas to temperatures of about 10,000 degrees Fahrenheit and for about 30 microseconds, Spheromak has created instant plasma.
For that small fraction of a second, the plasma wraps itself around the magnetic field like a ring on a finger, or, as Goldenbaum likes to say, "like beads on a string."
"Of course," he adds, "astrophysical plasmas last billions of years. Ours are less than a second." The process, he adds, is quite similar to a bolt of lightning in a summer thunderstorm. For fractions of a second, the lightning does, in fact, heat the air around it to such high temperatures that it becomes plasma.
Nevertheless, the plasma movements within the Spheromak cylinder are recorded in the memory of a computer, and scientists hope that someday they will help them chart the patterns of plasma movements that will enable them to design a nuclear-fusion reactor.
Most scientists do not expect construction of a prototype fusion reactor before the turn of the century, but they figure that within five years they can reach the break-even point where they can create a fusion process that produces at least as much energy as it uses up.
Maryland's $2.5 million-a-year plasma and fusion energy studies program is one of five leading university plasma research programs in the nation. A $2.7 million addition to the campus energy research building, under construction since last July, is expected to be completed by early next year.
Worldwide, thousands of scientists are working on a variety of projects and programs aimed at duplicating solar fusion on earth. In the United States, such efforts are under way at major government-sponsored national research labs at Oak Ridge, Princeton, Los Alamos and Livermore and in private industry, in addition to university centers such as Maryland.