Powerful new X-ray beams 100 times brighter than any ever produced are not the kind your dentist would use, unless he wanted to look at the atoms in your teeth.

"These X-rays are 10 million to 100 million times more powerful than the ones used by dentists," Arthur Bienenstock, director of the Stanford Synchrotron Radiation Laboratory said Wednesday as he discussed the breakthrough research.The intense, narrow beams achieved by the Stanford scientists, who worked with researchers from other labs, have enormous potential for medicine and industry, Bienenstock said.

"Scientists will be able to look at the structure of proteins too small for standard techniques," he said. "The modern era of genetic engineering arises from our ability to determine atomic arrangements in proteins."

The X-rays also could be used to study chemical reactions as they occur and surfaces of everyday industrial materials subject to corrosion or wear and tear. And they could be used to study superconductors and semiconductors to detect defects at the molecular level.

"Every order of magnitude in the qualities of a light source results in new, in most cases unexpected, unanticipated science," said Herman Winick, deputy director of the lab.

Synchrotron radiation, the electromagnetic radiation emitted by electrons forced into curved paths by magnetic fields, is the most powerful source of vacuum ultraviolet radiation and X-rays.

The new X-rays, Winick said, approach the performance level anticipated for synchrotron radiation labs in design and construction in Europe, Japan and the United States. Scientists at these labs, which are expected to be operating by 1995, hope to study the molecular structure of materials and human tissue.

"A typical size of an atom is about 100 millionths of an inch," Bienenstock said, "and these X-rays allow you to see arrangements on that scale."

The team at Stanford, which included the Stanford Linear Accelerator Center, the Argonne and Brookhaven national laboratories, and the Lawrence Berkeley Laboratory, achieved the new X-rays during a 12-day run last December. The results were reported recently at a meeting of the American Physical Society in Baltimore.

The increase in X-ray brightness was reached using a bunch of electrons whipped at nearly the speed of light around a 1.3-mile ring. During the December run, the ring was operated at 7.1 billion electron volts.

The scientists made the bunch extremely small with magnets that focused the electrons so the X-rays appeared to be emitted almost from a single point.

The electrons were then sent through a wiggly path using magnets with alternating polarity. Each time the path wiggled the electrons gave off radiation to produce greater brightness.