HIGH EXPLOSIVES

While the size of atomic bomb explosions dwarfed anything that conventional explosives could achieve, the success of atomic bomb design depended on innovations in these conventional explosives. Conventional explosives work by rapidly burning to create hot gases at high pressure, which expands to cause an explosion. Manhattan Project scientists used explosives for a counter-intuitive purpose: to do the precision work of assembling the critical mass in the bomb core. While explosives propelled the "bullet" into the target in the gun-type assembly, precision explosives were even more important in the implosion design. There were two difficult problems in explosives research. First of all, the explosives needed to be arranged such that the shock waves that they created would be spherically symmetric, and would uniformly compress the fissile material in the bomb core. If the explosives did not maintain this symmetry, then the core would deform and the bomb would fizzle. Second, not only did the shock waves need to be precisely directed, they also had to be triggered simultaneously. Any delay between explosives would have the same effect as failing to direct the shock waves properly.

To solve the timing problem, Los Alamos scientists designed a fuze that worked by vaporizing a metal bridge. As this metal vaporized, the explosives around the bomb would be triggered all at once. Shock waves were focused inward by designing "explosive lenses," which operated much as optical lenses do. Just as a magnifying glass concentrates light onto a focal point, so did these explosive lenses concentrate the shock waves onto the center of the bomb. Research in explosives was done along with other bomb design work at Los Alamos, though the dangerous nature of the explosives experiments and fabrication meant that it was located off the mesa at the S-Site facility.

• Gun-type Design
• Implosion Design
• Initiators and Polonium
• High Explosives
• Fuzes and Detonators
• Hydrogen Bomb

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