How does the atomic bomb work?

Answer 1

Simple explanation:Conventional bombs explode as a result of chemical reactions, but the atoms themselves that make up the chemicals stay unchanged by those reactions. On the other hand, the "Atomic Bomb", also called a "Nuclear Bomb", is so named because it explodes as a result of reactions which actually do change the atoms. When those atoms are changed in this way, they create explosive energy as a direct result of the changes of the atoms.

Technical Answer: To explain how a nuclear weapon (sometimes called an atomic bomb) works, we need to jump around a bit to pick up the necessary ideas that we'll knit together to build this critter. We can start by separating the nuclear weapons into two basic types: there is the fission weapon and there is the fusion weapon. We'll start with the first one and go from there. But first we need to review some physics. Buckle up. Let's take a ride.

Among those quirky elements at the upper end of the Periodic Table we find a couple or three that are fissile. What that means is that if they capture a neutron, they can fission; the atomic nucleus can be broken apart. They also spontaneously fission, and they do this to some extent all the time. All the elements at the upper end of the periodic table are unstable and undergo radioactive decay; they have no stable isotopes. But this is just a "breakdown" of the nucleus and the ejection of a particle or two and some energy. Fission is actually a "splitting" of the nucleus of an atom. It breaks into "chunks" we call fission fragments. A neutron or two or three is also ejected in the event. You can imagine the violence of this phenomenon on the atomic scale. It's horrendous. A lot of energy is released, and this is the key to the use of these materials in a weapon.

When we consider the fissionable materials, there is a threshold called critical mass associated with them. When it is exceeded, that is, when we "put together" enough material to exceed the critical mass, the material will spontaneously begin to fission. This is because a tiny number of spontaneous fissions occur naturally all the time, and the neutrons released in these events, which always are occurring, will start a chain reaction. (This is actually how an atomic bomb blast or the chain reaction in a nuclear reactor begins.) Enough material is around, that so-called critical mass, that a chain begins spontaneously. There is no way to stop this from happening if critical mass is reached. It will always occur. But which elements do this?

It is uranium and plutonium that we are most familiar with as nuclear weapons materials. Let's just look at them. As regards uranium, only the specific isotope U-235 will work for this application. Over 99% of the uranium in the ground is U-238, and only a tiny portion of the metal is the isotope U-235. We have to refine the uranium to separate the tiny bit of that lighter isotope out to make a weapon. And that's no mean feat! It takes a lot of equipment and energy to process the material and concentrate the preferred isotope sufficiently. We call this process enrichment, and the finished product is enriched uranium. Plutonium is created by exposing uranium to the neutron flux in an operating nuclear reactor and letting it "soak up some neutrons" and transform into plutonium. This is the most common approach to obtaining weapons materials that the nuclear powers use. So we have our nuclear material, and all we need to do now is make a bomb.

There is a thing called "geometry" that we associate with nuclear weapons. It speaks to the sizes and shapes of the sub-critical masses of the fissionable material that we are using in the bomb. It will probably also include how they will be brought together to achieve critical mass. Certainly there will be some safety features associated with the geometry, the physical design of the bomb. Remember that if we put enough fissionable material together to cause a chain reaction to begin, lots of energy will be liberated very quickly. And this energy will serve to "push apart" the material that was brought together to create the critical mass. So just "joining together" sub-critical masses of material won't work for a bomb because the immediate release of energy will force the material apart. There are a couple of basic ways to arrange the sub-critical masses and "force" them together, but that's what will have to be done. The fissionable material will have to be "driven together" somehow to make it work well. This is where conventional explosives come into the picture.

In a bomb, the sub-critical masses will be "blasted together" by a chemical explosive, and this blast will "hold" the material together for a split second to let the chain build to criticality and beyond to the point where the chain is actually supercritical. Proper design and construction will permit a good "burn" of the nuclear material with a large resultant release of energy. A triggering mechanism will set off the conventional charges and they will drive the sub-critical masses together. The "assembled" mass will be a bit more than critical, and the spontaneous fissions that are always occurring in the material will initiate a chain reaction. Atoms will spontaneously fission, the neutrons released will be captured by other nuclei, and they in turn will fission releasing more neutrons. The chain has begun and expands almost instantly. The periods of time associated with the initiation and buildup of the chain are ridiculously short. It all basically happens "in an instant" and the weapon detonates. This is the fission weapon, and a fission weapon is needed to set off a fusion weapon.

In nuclear fusion, protons are fused together to form helium nuclei - at least in the simplest form, which is what is used here. That is how our sun is operating now. At least mostly. Later in the sun's life, the fusion of heavier nuclei will be more predominate. Then heavier still. Anyway, it takes a lot of energy to force hydrogen nuclei (the protons) together and fuse them. This happens in an environment of extreme heat. Only the heat of a nuclear blast can create enough energy here on earth to fuse quantities of hydrogen nuclei into helium nuclei. (This though the laser pumped fusion reactor is still being experimented with.) The fusion of hydrogen, the fusing of those two protons and a pair of neutrons, is the hydrogen bomb. We effectively build a fission bomb "around" a supply of "hydrogen" and set it off to create the fusion explosion. It's really a huge blast. And that's the long and short of it.

There are some other "exotic" weapons out there. The fission-fusion-fission weapon is one that takes it a step further. It just uses the fusion device to trigger another fission device which is built into it. It's really hairy. There are neutron bombs, too, which just pack more "neutron producing material" in the package to generate more neutron radiation to kill things without increasing blast damage - which is already substantial. We've paved the road for you and given you a map to get you started. Should you wish to continue on down it, there will be some school work you'll have to master to fully appreciate the in's and out's of these notoriously quirky devices. Oh, and don't think you'll be "tickling the dragon's tail" any time soon. It takes a PhD and a security clearance above "Top Secret" to even get on the reservation, let alone get in the door.

Naturally we have some links you can follow to learn more, and those links can be found below.

Answer 2

-From Wikipedia (see Web Links to the left):
Nuclear fusion is the process by which multiple atomic particles join together to form a heavier nucleus. It is accompanied by the release or absorption of energy.

-From GSU.edu (see Web links to the left):
If light nuclei are forced together, they will fuse with a yield of energy because the mass of the combination will be less than the sum of the masses of the individual nuclei. If the combined nuclear mass is less than that of iron at the peak of the binding energy curve, then the nuclear particles will be more tightly bound than they were in the lighter nuclei, and that decrease in mass comes off in the form of energy according to the Einstein relationship. For elements heavier than iron, fission will yield energy.

For potential nuclear energy sources for the Earth, the deuterium-tritium fusion reaction contained by some kind of magnetic confinement seems the most likely path. However, for the fueling of the stars, other fusion reactions will dominate.

See the Web Links for more information about nuclear fusion and how it works.

Answer 3

An Atomic explosion occurs from the process of nuclear fission. This is where the nucleus of an atom(the part of the the atom which contains protons and neutrons? is split. This causes neutrons to travel at high speeds, sending theme crashing in to the nucleus of other atoms, repeating the process. The release of the neutrons generates an amount of force, the explosion of one atom is about enough to move a grain of sand. The huge chain reacton of all these atoms multiply together, creating a large explosion. Einstein figured out that energy and mass, like an atom, are related in his famous equation, Energy=mass x the speed of light squared(E=mc2). Basically, Atomic Bombs genereate their large explosions because of the large amounts of energy released during the chain reactions that occur during nuclear fission.

Answer 4

A fusion bomb uses hydrogen fusion to generate explosive energy. Deuterium and tritium (isotopes of hydrogen) are caused to fuse by a primary igniter. This igniter is a conventional fission bomb, which actually generates most of the destructive energy.