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Even though it came from a small company competing against the giants of the field, there was nothing modest about the announcement made last week by KMS Industries Inc. of Ann Arbor, Mich. The firm claimed that its scientists had briefly sustained a laser-generated fusion reaction and called its work a "definitive step" toward taming thermonuclear fusion--the same process that produces the explosive power of the hydrogen bomb and the vast heat and radiation of the sun.

As expected, the claim caused widespread excitement. It promised that fusion plants might some day supply mankind with practically unlimited energy. Indeed, an AEC spokesman called the feat "a small but significant initial step." But at week's end doubt was growing among some nuclear scientists that the laboratory had done anything more than Soviet and U.S. researchers had previously announced. In fact, it seemed quite possible that true thermonuclear fusion had not really occurred at all during the Ann Arbor experiments.

Fast Neutrons. Unlike the more familiar process of fission (in which energy is released by the breakup of atomic nuclei), fusion involves the combining (or fusing) of two nuclei of hydrogen. The reaction releases energy--primarily in the form of high-velocity neutrons--that scientists hope some day can be harnessed to generate electricity.

But controlled fusion can occur only under conditions of very high temperature and density that researchers have tried for years to produce by using powerful magnetic fields to squeeze or confine isotopes of hydrogen called deuterium and tritium. But even the best of these "magnetic bottles" --which require tremendous amounts of energy to operate--have so far been unable to provide the necessary temperature and density for more than a tiny fraction of a second.

Lately scientists have been turning to a more efficient tool for creating fusion: the laser. By heating a tiny pellet of deuterium or tritium with a powerful pulse of laser light, they cause the explosive evaporation of the pellet's surface. As the material sprays off, the rest of the pellet implodes. The hydrogen nuclei are thus forced together. As early as 1968, a team of Soviet researchers under Physicist Nikolai Basov, a Nobel laureate, reported that they had used lasers to ignite a brief but clearly detectable fusion reaction. Since then, their experiments have been repeated--and improved upon--in a number of countries, including the U.S., France, Britain and West Germany. But scientists are not yet certain that the burst of neutrons that characterizes such reactions is produced by true thermonuclear fusion or by the collision of relatively few fast-moving atomic nuclei in the compressed deuterium or tritium.

True Reaction. KMS had no such reservations about its work. It claimed to have produced true thermonuclear reactions in its various pellets. But when scientists looked a little closer at KMS's own disclosures, they noted an apparent inconsistency. In a letter to stockholders, KMS conceded that the experiments produced only a small number of neutrons--between 5,000 and 10,000.

According to accepted theory, if the other conditions of density and temperature reported by KMS had indeed occurred, the yield should have been at least 1 billion neutrons. The debate may be resolved when KMS opens its doors this week to a visiting contingent of the AEC scientists.

In spite of their skepticism about KMS's claims, scientists are optimistic that laser-induced fusion will some day become a practical source of unlimited energy. In fact, no less an authority on fusion than Edward Teller, a key figure in development of the H-bomb, is sure that the laser fusion researchers will eventually "succeed and that the effort will profoundly change our views on how man and matter can interact."

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