In the basement of a Cornell University engineering building, a large aluminum cylinder envelops microexplosions that one day, given sufficient federal funding, could contribute to developing the world's major hope for efficient electricity generation.

That hope is called nuclear fusion, the energy source of the sun and other stars in which hydrogen nuclei combine, or fuse, to produce huge amounts of energy. Cornell's contribution to this is a research method that, literally, hangs by hair-thin wires.

This so-called inertial confinement fusion research program has received its first two direct infusions of funds from the U.S. Department of Energy (DOE). The most recent award is for $150,000 a year over three years. In March, the DOE granted Cornell research support of $365,000 over two years, to be shared with collaborators at Imperial College, London, and the University of Nevada, Reno.

Cornell's program, presided over by plasma physicist David Hammer, the J.C. Ward Jr. Professor of Nuclear Energy Engineering, has been supported for the past four years by a small contract from the DOE's Sandia National Laboratories, Albuquerque.

Sandia and Cornell are coming from behind against another, better-funded area of inertial fusion energy research using a laser beam. In that method, a "driver" focuses a beam of laser light on a target containing hydrogen fuel. The irradiation results in an implosion which can, in turn, lead to fusion reactions. The laser concept has received the great bulk of federal research dollars, culminating with the National Ignition Facility, a $1.2 billion research center being built at Lawrence Livermore National Laboratory in California.

Researchers at Sandia and Cornell are developing a fusion system that uses X-rays instead of a laser beam and is called simply Z. It is far less costly than a comparable laser facility, says Hammer, perhaps only 20 percent of the cost. The Z machine, 90 feet in diameter, is designed to generate an extremely high power X-ray pulse which would create temperatures in the millions of degrees in the hydrogen fusion fuel. The direct generation of X-rays offers the promise of energy efficiency when compared with the huge power demands of a laser device. The laser inertial confinement system has very briefly produced fusion reactions, but this output was infinitesimal compared with the amount of energy required to power the laser.

The Sandia Z machine accumulates energy over a period of two minutes, and then, in a burst of current lasting a tenth of a microsecond, bombards its target, made up of 240 or more wisp-thin wires of tungsten or other metal strung together in a circular array. The wires explode, creating a hot ionized gas called a plasma. The intense magnetic field created by the current compresses, or "pinches," the plasma, generating X-rays. In a fusion reactor this powerful X-ray source could be directed at the hydrogen fuel. The Z machine is the world's most powerful producer of X-rays.

Hammer believes that the Sandia machine could lead to a bigger device that within a decade could produce net fusion energy (more energy coming out than is put in), even though the yield would be relatively small. "But even that would be an extraordinary accomplishment," he says.

To reach this goal, Hammer and his colleagues at Cornell's Laboratory of Plasma Studies -- Bruce Kusse, director of the laboratory, and John Greenly, research associate -- in collaboration with Imperial College and the University of Nevada, are using special instruments to try to understand exactly what happens to the wires at the moment of explosion.

However, the energy department's latest funding is to test a theory that the wires, as a result of the radiation they emit while imploding, become a thousand times more dense than a metal in its normal state. This theory, called radiative collapse, was first advanced in the mid-1950s by British and Russian scientists.

Cornell's research device, called a pulsed-power generator, is commanded by a yellow tank filled with transformer oil and capacitors, which are charged up to 40,000 volts each. This energy is then released into an aluminum cylinder in the form of a 400,000-volt pulse, where it evaporates an array of fragile wires of tungsten, titanium or nickel. X-ray photography is used to image the implosion.

In the real world of a commercial fusion power plant, says Hammer, some way would have to be found of threading an array of 240 wires once every second, as pulses of electricity bombard each assembly in a staccato of explosions. Hammer says that the wires would have to be replaced at least that often to make such a system economical.

Despite the promise of recent results in fusion research, Hammer believes that given the current level of government funding, commercial fusion is still three decades away.