Atomics.

[hypogy]

Move this if it was posted before, but I had a question.
Atom bombs. How do they work? I understand that the splitting of an atom causes a chain reaction, but what else happens?
And what determines the area-of-effect the initial explosion has?
Also, any information on hydrogen bombs would also be appreciated.

[Gil Hamilton]

Basically, an atomic bomb works like this.

You've got a big dense ball of crap called uranium and you've got a doohicky that shoots some glowy stuff called neutrons at it.

The nuetrons zip toward the uranium and high speeds, like George Jetson in a hover car travelling toward a floating arcology on a pole. And like George Jetson, neutrons are alcoholics, and crash into the uranium arcologies on poles.

The floating uranium houses go BOOM and and release their amazing potential energy stored up in the heart of the arcology. But three of the residents jump into their own cars and make an amazing high speed getaway and out run the blast of energy from the exploding Future Arcology on a Pole. These are other neutrons and they are very angry.

These three angry angry neutrons slam into other Amazing Future Arcolologies On Poles (Uranium atoms), which explode and send out a group of three other flying car neutrons, which hit other arcologies on pole, and pretty soon everything blows up really fast in a chain reaction! OMG!

Do this over a city with a big enough ball of uranium and it makes a large portion of that city into the Flintstones.

[Nephtys]

A Thermonuclear device, or multistage device, or Hydrogen bomb is basically an implosion-type fission bomb, with a Deuterium/Tritium core inside the plutonium. When the fission device goes off, a fusion reaction begins and the D/T releases additional energy, and neutrons to increase the efficiency of the fission reaction more.

The end result is a much more efficient, and more powerful yield.

[Surlethe]

Move this if it was posted before, but I had a question.
Atom bombs. How do they work? I understand that the splitting of an atom causes a chain reaction, but what else happens?

Very heavy element isotopes are naturally unstable; this is why they're radioactive. When a neutron is added to a heavy element, such as Pu-239 or U-235, the slight increase in energy causes the nucleus to split into two roughly equal parts, and a great deal of energy is given off. This is because the energy required to keep the two new atomic nuclei together is much less than the energy required to keep the initial isotope nucleus together; the energy has to be given off, since it doesn't show up in either of the final binding energies.

So, a neutron which hits a spare isotope's nucleus will cause it to split; but the split gives off more neutrons. If the hunk of isotope is big enough and dense enough, those neutrons will be absorbed by other nuclei, and there will be an exponential cascade of fissions; this is the infamous chain reaction.

And what determines the area-of-effect the initial explosion has?

The yield of the weapon. There is more information at the NWFAQ.

Also, any information on hydrogen bombs would also be appreciated.

Atomic nuclei naturally repulse each other; in nuclear fusion, nuclei absorb enough energy they bounce into each other, and fuse. This results in a net loss of energy as the nuclei fuse into a larger one which requires less energy to hold together. Since the conditions required to get hydrogen to fuse are almost identical to the conditions at the center of the sun, hydrogen bombs are actually powered by small fission bombs, which create the heat. This is what a multistage weapon is: the fission bomb goes off, which creates a bunch of heat and pressure; this causes the hydrogen to fuse, which, in turn, releases a whole lot more energy.

[Sea Skimmer]

A Thermonuclear device, or multistage device, or Hydrogen bomb is basically an implosion-type fission bomb, with a Deuterium/Tritium core inside the plutonium. When the fission device goes off, a fusion reaction begins and the D/T releases additional energy, and neutrons to increase the efficiency of the fission reaction more.

That’s a description of a boosted fission device, the fusion reaction adds virtually nothing to the yield of the device, it just works to improve the fission yield. With a true Teller-Ulam fission/fusion device, the material which undergoes fusion is a separate package (called a ‘the secondary’) placed alongside the plutonium or uranium sphere which is ‘the primary’. Radiation thrown off by the primary ignites the secondary, and if you desire multiple stages beyond that. Though even three stage bombs are very rare, with Tsar Bomba being the prime example (and even then, when tested it was only a two stage weapon)

[Winston Blake]

Move this if it was posted before, but I had a question.
Atom bombs. How do they work? I understand that the splitting of an atom causes a chain reaction, but what else happens?
And what determines the area-of-effect the initial explosion has?
Also, any information on hydrogen bombs would also be appreciated.

I'm going to go out on a limb here and assume you've never heard of wikipedia. That should give you a decent overview.

[Ariphaos]

For doing some math that isn't fully explained in the link Surlethe gives, check this link:

http://www.cddc.vt.edu/host/atomic/nukeffct/enw77b3.htm

[drachefly]

If you're wondering why these two nuclei that repel each other would suddenly start sticking, it's the strong nuclear force -- which is VERY strong, strong enough to hold them together against their electrical repulsion, but also VERY short-ranged.

[Gil Hamilton]

If you're wondering why these two nuclei that repel each other would suddenly start sticking, it's the strong nuclear force -- which is VERY strong, strong enough to hold them together against their electrical repulsion, but also VERY short-ranged.

I think it's more that the strong nuclear force is weaker than electromagnetism. Of the fundamental forces, electromagnetism has the mightiest wang. That's why a nucleus has to have alot of energy and get lucky in order to jump the Coulomb barrier and make sweet fusion with another nucleus, and even then it has to be a small one or the affair is a losing proposition when it comes to energy release (any element above iron).

[Ariphaos]

I think it's more that the strong nuclear force is weaker than electromagnetism. Of the fundamental forces, electromagnetism has the mightiest wang. That's why a nucleus has to have alot of energy and get lucky in order to jump the Coulomb barrier and make sweet fusion with another nucleus, and even then it has to be a small one or the affair is a losing proposition when it comes to energy release (any element above iron).

No, the strong nuclear force is significantly stronger than the electromagnetic force. You notice that atomic bombs are slightly more powerful than conventional? That's strong nuclear force versus electromagnetics. The electromagnetic force just has a wang as long as gravity's and some 10^40 times more powerful. But, even at that, it's still a lot weaker than the nuclear forces.

[Winston Blake]

I think it's more that the strong nuclear force is weaker than electromagnetism. Of the fundamental forces, electromagnetism has the mightiest wang. That's why a nucleus has to have alot of energy and get lucky in order to jump the Coulomb barrier and make sweet fusion with another nucleus, and even then it has to be a small one or the affair is a losing proposition when it comes to energy release (any element above iron).

It's a matter of range. The strong force's strength drops off much faster than inverse square. More than a few femtometers away and it's weaker than electromagnetism, but if you get much closer it quickly grows stronger. If it was absolutely weaker, nuclei wouldn't hold together.

[Patrick Degan]

Move this if it was posted before, but I had a question.
Atom bombs. How do they work? I understand that the splitting of an atom causes a chain reaction, but what else happens?

The mechanics of an atomic bomb aren't too difficult to grasp.

Basically, there are two types of fission bombs: the uranium-gun type (Little Boy) and the implosion device (Trinity-class bombs which are pretty much standard). The former essentially is a gun which fires a slug of uranium-235 down a tube at high velocity toward another slug of U-235 with a graphite ball nested in it: the graphite, when squeezed into the two U-235 slugs, releases neutrons at the moment of criticality which touches off the chain-reaction. Trinity and its descendants are the far more elegant and efficient types of A-bombs using plutonium-239, arranged into several wedge-shaped plugs around a graphite core; charges impel the plutonium plugs into an implosion to achieve critical mass and a city vanishes in a huge mushroom cloud. Although the uranium gun-type weapon is the easier one to build, the implosion bomb based on plutonium is the better mechanism because plutonium has a greater energy-density for its mass and is therefore the more fuel-efficent configuration.

A hydrogen bomb is somewhat more complex but also comprehensible. In the aforementioned Teller-Ulam configuration, a Trinity-type first stage is used to generate heat and radiation pressure which is focussed downward into the core of the device, which consists of a deuterium-tritium (or Lithium-6 Deuteride) core with a plutonium outer jacket and nested within what is known as a tamper, a hollow container fashioned with uranium-238. Radiation pressure causes the core to compress in on itself; the plutonium jacket is forced into criticality and triggers the second-stage blast which generates even more heat and radiation pressure which creates the required conditions for fusion to initiate. The kicker however is that the purpose of the fusion reaction is to release a flood of fast free neutrons to trigger fissioning of the uranium tamper, which powers the big blast. Fully 60% of a Teller-Ulam thermonuclear device's blast-yield actually derives from fission reactions, but without the fusion componnent the U-238 would not achieve criticality. And all this happens within the tenth of a second before the bomb casing disintegrates in the blast.