Despite the risks to Americans in Beirut, State Department recruitment officials said they get two to three times as many volunteers as they need to staff the U.S. Embassy there.

"There have always been more people who want to go than there have been jobs to fill," said Ronald I. Spiers, undersecretary of state for management, who is in charge of assigning State Department employes to embassies.

Recently State Department officials had "five or six" willing candidates under consideration for the ambassador's post, Spiers said. The position opened in May when Reginald Bartholomew ended his tour of two years and seven months, an assignment he reportedly asked the administration to extend.

The State Department has forwarded its nominee to President Reagan, who is expected to announce an appointment in six to 10 weeks, a White House spokesman said.

The number of volunteers often swells during a crisis, recruitment officials said, recalling the reaction to three recent events: the April 18, 1983, bombing of the embassy in west Beirut, which killed 63 persons; the Oct. 23 explosion that year at the U.S. Marine headquarters in which 241 military personnel died, and the Sept. 20, 1984, bomb blast that killed 20 persons at the embassy annex in the east Beirut suburb of Aukar.

Eugene Scassa remembers especially the weeks following the Sept. 20 attack. He was in Washington then, and responsible for assigning State Department employes to Middle East posts.

"After the explosion, I had a hundred or more expressions of interest, from [Foreign Service officers] all around the world," said Scassa, who volunteered to work in Beirut on three occasions. "The feeling was, this is the Foreign Service, this is what we do for a living and so whenever you have a crisis, people tend to pull together."

Many employes volunteer, recruitment officials said, because ordinary challenges are magnified in Beirut, a city where the government, on paper, competes daily on the streets with militias empowered by rival political parties or foreign governments.

"They go because the political challenge is there. . . . Operating within the security constraints is tremendous," said a young diplomat who twice volunteered for Beirut. "It's a test of ingenuity."

Others offer to go there, recruiters and volunteers said, because they are fascinated by the Lebanese culture, or convinced that their efforts make a difference.

Others ask to go because they know such a high-profile assignment will help their careers. "They think once they're done the Foreign Service will take care of them, and generally they do," said Edward Abington, an assignment officer.

The cowboys are drawn by the hazards, while others go for the "danger pay," which along with "hardship pay," said Abington, can add up to 50 percent to the typical $45,000 paycheck.

Scassa, a 24-year veteran of the Foreign Service who now works as deputy executive director of the Bureau of Inter-American Affairs, said the people who sent him telegrams or stopped by his office after the 1984 bombing sought neither the money nor the excitement.

"I don't think we're adrenalin junkies in that way. Sometimes there are a lot of routine things that need to be done even in that environment," said Scassa, a husband and the father of three children. "I'm not talking about cowboys, but straight people with families and wants and concerns."

Washington has set down strict rules for U.S. diplomats in Beirut. They are not allowed to bring dependent spouses or children with them. Their movement around Christian-controlled east Beirut is restricted to well-traveled streets, and then only when necessary. Moslem-controlled west Beirut is off-limits.

The embassy staff, which by the 1970s was one of the largest in the Middle East, has been scaled back to about 47 Americans who work in the annex building in Aukar, north of the city, said Spiers.

Most embassy employes stay for 18 months to two years, and ambassadors stay two to three years. But terrorism has imposed its own timetable: since October 1983, when the first major attack on the embassy took place, at least 19 positions have been vacated because the Americans who filled them were killed.

"I went in with my eyes closed," said the young diplomat, who arrived on his first assignment in Beirut just three hours after the April 1983 bomb explosion had killed 17 of his colleagues and turned the seven-story pinkish building to rubble. "It was not as clear then as it is now that diplomats were targets."

This summer he will return, this time to help smooth the transition for the new ambassador and the three new employes who will go with him. "It's always a matter of weighing the job to be done with the risks," he said about his decision to return to Beirut. Then he paused, and added: "It's fascinating and a lot of fun."