Atlantic Research Corp., the fast growing, Alexandria-based, diversified high technology firm, hopes to continue 20 percent growth in profits for the forseeable future, the corporation's chairman said yesterday.

Although ARC, whose profits have increased by at least 20 percent a year since 1977, dislikes forecasting, Chairman Coleman Raphael told a group of investment analysts yesterday, "It is our intention to continue to shoot for 20 percent growth in our activities."

Raphael also said the company will continue its diversification plans to maintain job security for its employes whose work depends on government contracts. As for the first quarter this year, President William Borten said, "there are a lot of smiling faces at ARC." Growth is similar to that during last year's first quarter, Borten said.

When asked how the company will meet its 20 percent growth commitment, Raphael said, "It is our goal to try to exceed the 20 percent."

About 60 percent of Atlantic Research's revenues come from building missiles for the government, placing the company in a good position to capitalize on the Reagan administration's drive to increase defense spending, according to a report by Ferris & Co. Inc.

One of its special projects, Raphael said, is building smokeless rockets. Another is producing an oil-like fuel made from coal.