Between the two steel mesh fences that form the outside perimeter of the Federal Penitentiary here, there are 16 long cylindrical rolls of razored concertina barbed wire, each meshing with the other and stacked up until the last roll fixes itself like a vise to the top of the outermost fence.

Looking down between the fences are eight glass-and-concrete gun towers manned 24 hours a day by sharpshooting guards with weapons ranging from automatic carbines to wired missiles that can bring down a helicopter. Security is just as tight behind the fences. Eight iron-grilled doors separate the prisoners from the outside; each door is controlled by coded electronics signals.

Closed-circuit television cameras are everywhere. So are the prison's 188 guards, who seem to appear in the broad corridors the instant there's even a hint of trouble behind the bars.

Welcome to the Federal Penitentiary at Marion, the nation's maximum security prison, which was built on the Crab Orchard National Wildlife Refuge in southern Illinois for $16 million in 1963. That was the year Alcatraz was closed and its inmates transferred here.

The inmates are men who murdered policemen, FBI agents or other inmates. These are men in prison for armed bank robberies, armed hijacking of airliners and armed escapes from other prisons. These are men whose prison sentences average 37 years, more than three times the national average.

Here are Mafia chieftains who've stayed out of prison for years and criminals so common they've spent most of their lives in prisons. And a man who's so unmanageable he's been in 28 prisons in the last five years. And another who has been transferred so often from prison to prison that he's spent almost as much time on prison buses as in prison. Marion is home for the most rebellious, assaultive and murderous inmates in the federal prison system. Welcome to the New Alcatraz.

While other Americans may debate the role of prisons and how tough to be in handling violent criminals, at Marion there's very little debate. It's on the far end of the spectrum of tough prisons and energies here are directed toward maintaining control over the prison's desperate occupants.

"Most offenders in Marion have gone through other federal institutions. They have graduated to Marion, if you will," says Harold G. Miller, a crew-cut 51-year-old veteran of Alcatraz who is now warden of the Marion penitentiary. "What we have here are the very assaultive, the most notorious escape risks, the kinds of people whose day-to-day habits and management problems show they need to be in Marion."

Right now there are 325 inmates in Marion, down from 475 five years ago, before the FBI turned over enforcement of bank robberies and car thefts to the states. Sixty percent are white, 30 percent are black, most of the rest are Hispanic and Indian. More than 25 percent are bank robbers and more than 80 of the inmates are "lifers" whose chances of ever getting out are not good.

The list of Marion inmates reads like the FBI's "most wanted" list on post office walls. Robert Platshorn, 38, serving 64 years for being the leader of the South Florida marijuana smuggling ring called the "Black Tuna." Everett Van Burkett, 33, a convicted bank robber accused of killing two inmates in other federal prisons. Garrett Trapnell, 44, serving a life sentence for hijacking a TWA jet for a $300,000 ransom. Bernard Welch, 41, the accused murderer of Washington cardiologist Michael Halberstam. Henry Gargano, 50, serving 199 years for killing two policemen after robbing a suburban Chicago bank. Also here is Gargano's partner, Ronald Del Raine, 51, who is serving 204 years for the same crime.

The toughest job prison authorities have at Marion is keeping all these inmates penned up. There have been 12 full-fledged escape attempts at Marion, five of which succeeded in springing inmates over the fence. All were found and brought back to Marion, however. No inmate has ever escaped permanently from Marion.

"We discover plans for an escape attempt every few weeks," Warden Miller says. "Maybe you shake a man down and you find him in possession of a small piece of a hacksaw blade or you find a bar partially cut or you'll find a screen that's been tampered with in the recreation yard or you'll find a few homemade tools stashed in the recreation yard. These are all definitely the initial stages of escape attempts."

In a way, Gargano and Del Raine typify the Marion inmate. In 1975, Gargano was one of five inmates listening to a lecture on labor conditions in Mexico in the prison visiting room, which is near the front lobby. While the lecturer droned on, the five inmates slipped out of the half-darkened room and used an electronic device they had fashioned in the prison shop to open up the three doors between them and freedom. To their surprise, all three doors opened at once and they fled into the thickening evening mist.

Their escape didn't last. Three days later, three were caught in Salem, Ill., 70 miles away, and the next day Gargano was caught in Bloomfield, Ind., 30 miles farther on. The fifth was captured about two weeks later in Winnipeg, Canada, where he held people hostage while robbing a bank. Gargano was returned to Marion and served a year in what inmates call "the hole."

"It was worth it," Gargano said. "I'd do it again just to get out of here for four days."

With three other inmates, Del Raine tried to escape from Marion three months ago. The four men spent months cutting through cell block bars with just the sliver of a hacksaw blade, then raced through the open bars one night in a wild bolt for freedom. One made it as far as the inner fence, the other three didn't even get that far before they were caught. Like his "rappie" (codefendant) Gargano, Del Raine doesn't regret it even though he figures it was something like his eighth escape attempt from prison.

"It was a perfectly workable, feasible escape possibility," Del Raine told The Washington Post while he sat handcuffed across a table from a reporter when taken from the detention unit where he was put after his escape attempt. "The security weakness was there . . . it was spotted by an Alcatraz veteran . . . the work was done . . . we had them. Even the guards admit it. Just a few little circumstances went wrong . . . . "

There is as much mayhem in the lives of Marion inmates inside the prison walls as there has been outside the walls. In the 17 years the prison has been open, five Marion inmates have committed suicide, 18 have been murdered and one guard has been beaten to death. Often, the inmates make their own liquor from the apples and raisins they smuggle out of their mess hall. Fist fights and assaults with handmade weapons are frequent enough to keep a full-time doctor and orderly busy treating emergency cases.

"My guess is that we see an inmate once every two weeks suffering wounds from violence," Miller concedes. "Maybe I shouldn't go that far. I'd say we're averaging one a month."

To hear some inmates tell it, the violence inside the walls is inflicted on occasion by the guards. Says inmate Del Raine: "If you do a little something to them, they'll beat you. They'll not only beat you, they'll knock you down and kick you. In '72, they kicked a fellow's teeth out here. A couple of weeks ago, they beat a fellow up, punched him in the face, squeezed his scrotum and kicked him in the face."

In reply, Miller turns grim and states flatly: "No, we do not beat inmates here in Marion. It's one thing we absolutely will not allow."

How does he control the violence at Marion? He separates the five regular cell blocks, meaning that the 50 to 60 prisoners in each go to movies, recreation and the prison yard together. They are never permitted to talk to prisoners from another cell block. Meals are staggered so that cell blocks eat alone. Prisoners are housed one to a cell and are locked behind their cell doors every night at 10:30 p.m. until 6:15 the next morning.

There used to be a work program at Marion, employing as many as 173 inmates printing government pamphlets and making metal desks and tables. But in January of 1980 the inmates called a two-day work strike. They struck again from March 17 until April 7, 1980. The inmates struck a third time, starting Sept. 15, 1980 and even though many inmates wanted to work, nobody did. The word went out: Anybody seen walking down the corridors to work was a dead man.

The inmates presented Miller with a list of demands before they would consider returning to work. Among them were three T-bone steaks a month and conjugal visits from their wives and girl friends. "Stuff that wasn't even within our authority to discuss," says Miller. The warden shipped Marion's printing press and sheet metal presses to other prisons and closed the prison factory.

"There was no sign whatever that the inmates were willing to go back to work," Miller says today. "I suspect that the people who called the strike lost control of the situation, to where they couldn't have said: 'Let's go back to work.' It was too late to do that."

The inmates have a darker suspicion. They suspect that Miller closed down Marion's work program to stop them from producing homemade weapons.