The Cardinal of the Kremlin - Tom Clancy [75]
"Okay, what do we know about this test they ran?" It was Gregory's turn again. "Sir, we know that it came from Dushanbe because the only other high-energy laser sites, at Sary Shagan and Semipalatinsk, were under the visible horizon-I mean, they couldn't see the satellite from there. We know that it wasn't an infrared laser, because the beam would have been seen by the sensors on the Cobra Belle aircraft. If I had to guess, sir, I'd say that the system uses the free-electron laser-"
"It does," Judge Moore noted. "We just confirmed that."
"That's the one we're working on at Tea Clipper. It seems to offer the best potential for weapons applications."
"Can I ask why, Major?" the President asked.
"Power efficiency, sir. The actual lasing occurs in a stream of free electrons-that means they're not attached to atoms like they usually are, sir-in a vacuum. You use a linear accelerator to produce a stream of the electrons and shoot them into the cavity, which has a low-energy laser shining along its axis. The idea is that you can use electromagnets to oscillate the electrons crosswise to their path. What you get is a beam of light coincident with the oscillation frequency of the wiggler magnets-that means you can tune it, sir, like a radio. By altering the energy of the beam, you can select the exact light frequency you generate. Then you can recycle the electrons back into the linear accelerator and shoot them back into the lasing cavity again. Since the electrons are already in a high-energy state, you gain a lot of power efficiency right there. The bottom line, sir, is that you can theoretically pump out forty percent of the energy you pump in. If you can achieve that reliably, you can kill anything you can see-when we talk about high energy levels, sir, we're speaking in relative terms. Compared to the electrical power that this country uses to cook food, the amount needed for a laser defense system is negligible. The trick is making it really work. We haven't done that yet."
"Why not?" The President was interested now, leaning forward slightly in his chair.
"We're still learning how to make the laser work, sir. The fundamental problem is in the lasing cavity-that's where the energy comes off the electrons and turns into a beam of light. We haven't been able yet to make a very wide one. If the cavity is too narrow, then you have such a high power density that you fry the optical coatings both in the cavity itself and on the mirrors that you use to aim the beam."
"But they've beaten the problem. How do you think they i did it?"
"I know what we're trying to do. As you draw energy into the laser beam, the electrons become less energetic, okay? That means you have to taper the magnetic field that contains them-and remember that at the same time you have to continue the wiggling action of the field, too. We haven't figured that out yet. Probably they have, and that probably came from their research into fusion power. All the ideas for getting energy out of controlled fusion are concerned with using a magnetic field to contain a mass of high-energy plasma-in principle the same thing we're trying to do with the free electrons. Most of the basic research in that field comes from Russia, sir. They're ahead of us because they've spent more time and money in the most important place."
"Okay, thank you, Major." The President turned to Judge Moore. "Arthur, what does CIA think?"
"Well, we're not going to disagree with Major Gregory-he just spent a day briefing our Science and Technology people. We have confirmed that the Soviets do have six free-electron lasers at this place. They have made a breakthrough in power output and we're trying to find out exactly what the breakthrough