Command and Control

Our troops guarded [the atomic bombs], but we didn’t own them…. Civilian-controlled, completely. I remember sending somebody out… to have a talk with this guy with the key. I felt that under certain conditions — say we woke up some morning and there wasn’t any Washington or something — I was going to take the bombs. I got no static from this man. I never had to do it or anything, but we had an understanding.

The arrangement seemed necessary, given the rudimentary nature of command and control in those days. “If I were on my own and half the country was destroyed and I could get no orders and so forth,” LeMay explained, “I wasn’t going to sit there fat, dumb, and happy and do nothing.”

Work on the hydrogen bomb gained more urgency after it became clear that the Soviet Union was trying to build one. A few days after Truman’s announcement that the United States would develop the Super, the British physicist Klaus Fuchs confessed to having spied for the Soviets. At Los Alamos, Fuchs had worked on the original design of the implosion bomb and conducted some of the early research on thermonuclear weapons. In January 1951, despite a year of intense effort, American scientists were no closer to creating a hydrogen bomb. Teller had proposed using a fission device to initiate the process of fusion. But he could not figure out how to contain the thermonuclear reaction long enough to produce a significant yield. The mathematician Stanislaw Ulam suggested a couple of new ideas: the hydrogen fuel should be compressed before being ignited, and the detonation of the bomb should unfold in stages. Teller was greatly inspired by Ulam’s suggestions, and in March 1951 the two men submitted a paper at Los Alamos that laid out the basic workings of a thermonuclear weapon—“On Heterocatalytic Detonations I: Hydrodynamic Lenses and Radiation Mirrors.” And then they applied for a patent on their H-bomb design.

Ulam had called his initial proposal “a bomb in a box.” The Teller-Ulam design that emerged from it essentially placed two fission bombs in a box, along with hydrogen isotopes like deuterium and tritium to serve as thermonuclear fuel. Here is what would happen, if everything worked as planned: an implosion device would detonate inside a thick metal canister lined with lead. The X-rays emitted by that explosion would be channeled down the canister toward hydrogen fuel wrapped around a uranium-235 “spark plug.” The fuel and the spark plug would be encased in a cylindrical layer of uranium-238, like beer inside a keg. The X-rays would compress the uranium casing and the hydrogen fuel. That compression would make the fuel incredibly dense — and then would detonate the uranium spark plug in the middle of it. Trapped between two nuclear explosions, the first one pressing inward, the second one now pushing outward, the hydrogen atoms would fuse. They would suddenly release massive amounts of neutrons, and that flood of neutrons would accelerate the fission of the uranium spark plug. It would also cause the uranium casing to fission. All of that would occur within a few millionths of a second. And then the metal canister holding everything together would blow apart.

The physics and the material science behind the Teller-Ulam design were highly complex, and there was no guarantee the bomb would work. It relied on a concept, “radiation implosion,” that seemed plausible in theory but had never been accomplished. X-rays from the detonation of the first device, called the “primary,” would have to be accurately focused and reflected onto the “secondary,” the cylinder housing the fuel and the spark plug. Using X-rays to implode the secondary was a brilliant idea: the X-rays would move at the speed of light, traveling much faster than the blast wave from the primary. The difference in speed would prolong the fusion process — if the interaction of the various materials could be properly understood.

The steel, lead, plastic foam, uranium, and other solids within the bomb would be subjected to pressures reaching billions of pounds per square inch. They would be transformed into plasmas, and predicting their behavior depended on a thorough grasp of hydrodynamics — the science of fluids in motion. The mathematical calculations necessary to determine the proper size, shape, and arrangement of the bomb’s components seemed overwhelming. “In addition to all the problems of fission… neutronics, thermodynamics, hydrodynamics,” Ulam later recalled, “new ones appeared vitally in the thermonuclear problems: the behavior of more materials, the question of time scales and interplay of all the geometrical and physical factors.” And yet the Teller-Ulam design had an underlying simplicity. Aside from the fuzing and firing mechanism that set off the primary, there were no moving parts.