Atomic Bombs

That would vary depending on the type of bomb it was.

This work is currently, in the US, only being done at PANTEX, outside Amarillo, TX. It is very specialized work.

Examples:

• A WW2 MK-III Fat Man took roughly 3 days to assemble or disassemble and was partially armed on the ground. This required a crew of 40 to 50 highly trained men.
• The MK-4 that replaced the MK-III took only about 4 hours to assemble or disassemble and under a half hour to arm or disarm in flight. This could be done with about a half dozen men.

An atomic bomb contains 1) ordinary explosives, 2) certain radioactive elements, and 3) a structure built of other elements that help to trigger the nuclear explosion. A nuclear weapon is essentially a mechanism to initiate the fission of heavy elements (such as uranium and plutonium) into smaller atoms.

An atomic bomb basically contains one or more masses of a fissile element. They are pushed together by the detonation of a small explosive to form what is called a supercritical mass(a critical mass is sufficient material to sustain a chain reaction). When the atoms split, they release neutrons. The neutrons released by one split triggers more splits, which trigger more splits, and so forth in a chain reaction. The reaction spreads throughout the critical mass practically instantaneously. In microseconds, several moles of atoms have a small part of their mass turned to energy, enough to create a fireball with a temperature of millions of degrees. This energy creates the heat pulse and destructive shock wave of the bomb.

H-Bomb

The hydrogen bomb, or thermonuclear weapon, uses the heat and pressure of the atomic chain reaction to cause fusion of a lighter element (hydrogen), which releases more energy per atom than fission. Some hydrogen bombs create even greater energy by using the fusion reaction to trigger yet another fission reaction in a tamper or blanket of uranium around the bomb. The fission-fusion-fission design creates the most powerful nuclear explosives, up to 100 megatons (of TNT) or more. But very few of these huge bombs were ever built, and none are known to exist today.

Yes.

• Tactical
• Strategic

• Fission - uranium, plutonium, composite
• Fusion

• Solid core
• Levitated core
• Boosted core

• Conventional fusion - 90% fission from U-238 fusion tamper
• Clean fusion - ~5% fission mostly from primary & sparkplug
• Dirty fusion - bomb is salted with elements intended to intensify fallout
• Neutron bomb - a small Clean fusion bomb intended to intensify neutron radiation

etc., etc., etc.

The term atom bomb (or atomic bomb) usually refers to a bomb that obtains its energy solely through the process of nuclear fission.

However technically the term is considered interchangeable with nuclear bomb, and can refer to any bomb obtaining its energy through either nuclear fission, nuclear fusion, or any combination of the two processes.

It's not from the atomic blast The smoke trails were not caused by the blast itself, but by smoke rockets that created contrails to provide points of reference for measuring the shock wave caused by the nuclear blast.

In the first few milliseconds after a nuclear detonation, the fireball and shock wave are indistinguishable, but soon after, the fireball cools a little and the shock wave continues on beyond it. The shock wave is a layer of high density air that expands out from the blast very rapidly. In nuclear testing, the scientists and engineers wanted to be able to track the progress of the shock wave well after it went beyond the fireball. So, they launched smoke rockets well behind the detonation site seconds before detonation. The dense layer of air acted as a sort of lens, refracting the image of the smoke rockets behind it, and allowing those working on the project to calculate the shock velocity and other properties as a scientific function. == ==

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.

An atomic bomb is any bomb which obtains its destructive energy from the excess binding energy of atomic nuclei. The term is most commonly applied to bombs that release the excess binding energy of heavy atoms by fissioning them to form lighter atoms, but can equally correctly be applied to bombs that release the excess binding energy of light atoms by fusing them to form heavier atoms (however such bombs are most commonly called hydrogen bombs).

The fine details of this are somewhat blurred as most modern nuclear weapons use some combination of both fission and fusion, regardless of what they are called (e.g. dial-a-yield tritium gas fusion boosted atomic bombs, conventionally built hydrogen fusion bombs usually get more than 90% of their yield from fast fission of their depleted uranium tamper) to optimize their characteristics.

The bombs used in ww2:

1. Gadget, sphere 5 feet in diameter, weight 10000 pounds, yield ~20 kilotons
2. Little Boy, 10 feet long and 4 feet in diameter, weight 9000 pounds, yield ~13 kilotons
3. Fatman, 10 feet long and 5 feet in diameter, weight 10000 pounds, yield ~22 kilotons

• SADM, sphere 11 inches in diameter, weight 50 pounds, yield 10 tons to 1 kiloton depending on configuration
• Ivy Mike, 20 feet tall and 6.7 feet in diameter, weight 164000 pounds, yield 10 megatons
• Tsar Bomba, 26 feet long and 6.9 feet in diameter, weight 60000 pounds, yield 50 to 58 megatons (depending on method of measurement)
• etc.