Atomic bomb implosion

Precisely controlled detonations are used to create an implosion of fissionable material to achieve critical mass in the explosion of an atomic bomb (See Vol 1, pp A499-504)... 

A three-dimensional squeeze inward was implosion. Neddermeyer had just defined a possible new way to fire an atomic bomb. The idea had been suggested previously, but no one had carried it beyond conversation. At a meeting on ordnance problems late in April, records the Los Alamos technical history, Neddermeyer presented the first serious theoretical analysis of the implosion. His arguments showed that the compression of a. .. sphere by detonation of a surrounding high-explosive layer was feasible, and that it would be superior to the gun method both in its high velocity and shorter path of assembly. ... 

The complexity of the project for all the effort and support meant that atomic bombs (actually a misnomer, a more accurate name would be nuclear bomb) would not be available until 1945 and made the proposed target shift from Germany to Japan. But by July 1945 an implosion bomb was ready to be tested several days ahead of schedule. 

The plutonium-235 implosion assembly, nicknamed Fat Man, was used in the bombing of Nagasaki 3 days later. On the morning of the bombing, Japan s Supreme Council for the Direction of the War met in the prime minister s bomb shelter. The meeting was deadlocked because some still wanted to continue the war. After the second use of an atomic bomb, Japan surrendered. 

The success of the Trinity test meant that a second type of atomic bomb could be readied for use against Japan. In addition to the uranium gun model, which was not tested prior to being used in combat, the plutonium implosion device detonated at Trinity now figured in American Far Eastern strategy. In the end Little Boy, the untested uranium bomb, was dropped first at Hiroshima on August 6, 1945, while the plutonium weapon Fat Man followed three days later at Nagasaki on August 9. 

Stanistaw Ulam (1909-1984), first associated with the University of Lwow, then professor at the Harvard University, University of Wisconsin, University of Colorado, Los Alamos National Laboratory. In Los Alamos Ulam solved the most important bottleneck in hydrogen bomb construction by suggesting that pressure is the most important factor and that sufficient pressure could be achieved by using the atomic bomb as a detonator. Using this idea and an idea of Edward Teller about further amplification of the ignition effect by implosion of radiation, both scholars designed the hydrogen bomb. They both own the US patent for H-bomb production. 

---