Especially in terms of the Tsar Bomber – a relatively large weapon – which caused the biggest nuclear explosion ever. If nukes deal with atom sized particles, why does a bigger sized weapon = bigger explosion?
Unsure if correct flair but when dealing with nuclear weapons a few could apply
In: Engineering
The yield is indirectly related to the actual size of the weapon, because we’re dealing with nuclear chain reactions here, the amount of fissile material determines the yield. But, the fissile material has to be close to more fissile material to continue the chain reaction. What will happen is that the core of the bomb with explode too quickly and some of the fissile material will be pushed out of the core before it has any time to join in the chain reaction. The gadget – the first plutonium based atomic bomb – solved this problem by using conventional explosives arranged in a sphere around the plutonium core to ‘smoosh’ the plutonium together to get a good chain reaction going. Later designs added things like tampers – heavy materials used to keep the bomb from exploding itself for just a few more milliseconds to get an even bigger chain reaction – and neutron guns – parts that inject extra neutrons into the core to speed up the reaction. The development of neutron guns that could be controlled externally led to ‘dial-a-yield’ bombs, where the operators beforehand can actually control how big the explosion will be by setting the neutron initiator to different settings. So more fissile material = bigger bang, that’s self-explanatory, but also you can be tricky with how you arrange the parts to get an even bigger bang out of the same amount of material.
Later designs are thermonuclear – they combine this fission bomb with hydrogen that was suitable to start a fusion reaction. Depending on how the parts are arranged you can have conventional explosives initiate a fission reaction which ignites a fusion reaction in hydrogen fuel and that in turn starts a fission reaction in other parts, for example if you made some of the parts out of uranium. That’s exactly what the Tsar Bomba was, just a very scaled-up thermonuclear bomb. So a bigger bomb can give you a bigger yield, but also, a small bomb can give you a pretty big yield anyway
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