WASHINGTON — The Soviet Union, for all its insistence that the United States stop work on its Strategic Defense Initiative, has itself been studying exotic anti-missile technologies such as laser beams for a longer time and more intensively than the United States, according to available evidence.
The expert consensus is that the Soviets match or lead the United States in the basic technology of lasers and particle beams--and perhaps even in converting the exotic technology into weapons.
At the same time, however, it is believed they remain significantly behind in computers, sensors and other support equipment vital to constructing an effective space-based missile defense system.
Hurling Energy Bolts
The most alarmed U.S. officials fear that the Soviets have made breakthroughs that could soon lead to weapons not only for defending against enemy missiles but even for hurling offensive bolts of energy from space down to Earth.
Assistant Secretary of Defense Richard N. Perle insists that the Soviets oppose research on SDI, colloquially known as "Star Wars," because they fear that the United States would stumble upon the same "offensive technologies" that they have found.
There is no evidence that space-based offensive weapons would be any more dangerous than Earth-based nuclear missiles. Yet Soviet leader Mikhail S. Gorbachev has said that the United States could use SDI weapons "against missiles, against satellites and against targets on Earth."
This much is known: Central Intelligence Agency and Defense Intelligence Agency officials say Soviet scientists have been conducting concentrated research on so-called "pulsed power" since the late 1950s or early 1960s. Of the four exotic "Star Wars" technologies--lasers, particle beams, microwaves and kinetic energy devices--the first three use pulsed power, which consists of intense bursts of energy.
In 1965, Andrei D. Sakharov, the Soviet dissident and physicist who helped to develop the Soviet hydrogen bomb, wrote one of the first important papers on how to create such a powerful electrical discharge, much like a lightning bolt.
Recently released from internal exile, Sakharov said Reagan's grand vision of a nationwide SDI umbrella against missiles was not technically feasible, but he criticized the Kremlin's demand that the United States stop developing the new technology.
"The research has started, and not only in the United States but we may infer that in this country something is being done," he added carefully in a statement that provided further support for the belief that Soviet scientists are conducting SDI-type experiments.
No Guarantee on Systems
Even if the Soviets succeed with the basic technologies in the laboratory, however, that does not guarantee that the concepts can be converted into anti-missile systems.
"Perhaps the biggest obstacles to Soviet success," said Deputy CIA Director Robert M. Gates, "are remote sensors and computer technologies--currently more highly developed in the West than in the U.S.S.R."
The congressional General Accounting Office, in a detailed 1982 study, estimated that the United States was five to 10 years ahead of the Soviets in the technologies related to turning lasers into weapons. These technologies include optical systems, early warning and target tracking sensors, microelectronics and data processing computers.
And what is true for lasers is probably true for the other exotic beam technologies as well, experts said.
Lasers, which emit powerful light beams that burn into their targets, appear to hold the greatest promise for use as weapons, U.S. experts say, and it is known the Soviets have made tangible progress in their development.
"Soviet achievements are impressive," Gates said. The Soviets, he said, have worked on three types of gas lasers--those using gases to produce the light beams--that the United States "considers promising for weapons applications."
In addition, he said, the Soviets have continued working on "certain types of lasers which the United States abandoned" because of cost or other factors. He added that they have been working on "other types of lasers that the United States has not seriously considered for weapons application until very recently." The CIA declined to identify the types.
Most of the results of the Soviet research have been kept secret. But in 1984, the Soviets reported an experiment in which a "free-electron" laser generated a beam of much greater intensity than the counterparts the United States has been researching, said Simon Kassel, a senior Rand Corp. engineer who specializes in Soviet research and development.
The free-electron laser--whose light is emitted when electrons change direction--is attractive both because it is particularly efficient in converting energy into light and because the light produced is of a frequency that passes more easily through air than the beams formed by most other lasers.