Radiation implosion

Radiation implosion is the compression of a target by the use of high levels of electromagnetic radiation. The major use for this technology is in fusion bombs and inertial confinement fusion research.

Radiation implosion was first developed by Klaus Fuchs and John von Neumann in the United States, as part of their work on the original "Classical Super" hydrogen bomb design. Their work resulted in a secret patent filed in 1946, and later given to the USSR by Fuchs as part of his nuclear espionage. However, their scheme was not the same as used in the final hydrogen bomb design, and neither the American nor the Soviet programs were able to make use of it directly in developing the hydrogen bomb (its value would only become apparent after the fact). A modified version of the Fuchs-von Neumann scheme was incorporated into the "George" shot of Operation Greenhouse.

In 1951, Stanislaw Ulam had the idea to use hydrodynamic shock of a fission weapon to compress more fissionable material to incredible densities in order to make megaton-range, two-stage fission bombs. He then realized that this approach might be useful for starting a thermonuclear reaction. He presented the idea to Edward Teller, who realized that radiation compression would be both faster and more efficient than mechanical shock. This combination of ideas, along with a fission "sparkplug" embedded inside of the fusion fuel, became what is known as the Teller–Ulam design for the hydrogen bomb.

Most of the energy released by a fission bomb is in the form of x-rays. The spectrum is approximately that of a black body at a temperature of 50,000,000 kelvins (a little more than three times the temperature of the Sun's core). The amplitude can be modeled as a trapezoidal pulse with a one microsecond rise time, one microsecond plateau, and one microsecond fall time. For a 30 kiloton fission bomb, the total x-ray output would be 100 terajoules.

...
Wikipedia