Nuclear Fusion

Nuclear fusion is the phenomenon in which multiple atomic nuclei combine to form a single, larger nucleus. Fusion mostly occurs under extreme conditions, due to the large amount of energy it requires. Thus, examples of fusion tend to be exotic; such as stellar nucleosynthesis, the creation of new elements, and thermonuclear weapons.

2,332 Questions
Nuclear Energy
Nuclear Physics
Nuclear Fusion

What are the requirements for nuclear fusion?

  • high temperature
  • high pressure
  • a fuel that can undergo fusion
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Can nuclear fusion be done on earth?

Yes.

Examples: The hydrogen bomb and the creation of new elements.

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Does nuclear fusion occurs at cooler temperatures away from the Sun?

Yes, in Red Dwarf Stars. However, the temperatures required for fusion are still pretty high, millions of degrees Celsius.

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Why does nuclear fusion have to take place at high temperature?

I believe it has something to do with stability, But as per new information, It doesn't necesarliy have to happen at high temperatures anymore. The NIF Facility in Livermore in California has recently sucessfully performed COLD Fusion, which is Fusion without the Super-High, Metal Melting temperatures. It is MUCH MUCH lower. So yeah. EA Game's Generals' USA faction's Cold Fusion Reactor is now a possibilty.

Note that the claims of low-temperature "Cold" fusion are as yet still unsubstantiated. Those claiming such advances are suspiciously secretive of their work; so much so, that they have the appearances of charlatans.

NIF is working not on "Cold" fusion (which is the premise that fusion can happen at relatively low temperature and pressure, no more than found inside a typical Internal Compustion Engine), but is instead experimenting with laser-compression fusion. LCF is a process where a small pellet of hydrogen is hit with several lasers for a very brief instant, compressing the hydrogen radically, to allow for fusion. In an LCF reactor, the hydrogen fuel is compressed to several thousand atmospheres by this laser, though the reactor itself isn't pressurized in the conventional sense.

Based on our current understanding of fusion, high temperature OR high pressure are required to overcome the natural repulsion of hydrogen nuclei. That is, to be able to push two hydrogen nuclei together, either enormous pressure is required, or extreme temperatures which change the matter composition and characteristics of hydrogen. No scientific basis for low-temperature or low-pressure fusion has ever been published or publicly demonstrated.

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What is Neuclear fusion in the sun?

Nuclear fusion in the sun happens when two hydrogen atoms (which have one valence electron) combined to form one helium atom (which has two valence electrons). When the two hydrogen's combine their valence electrons, that makes them have two. Which is why it forms helium because helium has two valence electrons. Nuclear fusion also happens on the stars.

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Why is nuclear fusion not currently used as an energy souce on earth?

We do not currently have the technical knowledge to produce controlled fusion reactors on a scale large enough to produce power. Right now, the only two viable uses of fusion are in the Sun, and in hydrogen bombs, but the latter is an uncontrolled reaction, not suited for use in a power plant.

The problem is that, in order to produce a fusion reaction, you need extremely high temperatures and pressures. That's easy for the Sun to do, because of its enormous mass and gravity, but on Earth it is a problem.

Once you have that fusion reaction going, then you need a way to contain it. Unfortunately, there is nothing that can hold the plasma needed for the fusion reaction, because it will burn through anything.

Since plasma is a charged stream, we can use magnetic fields to bottle it, so to speak, but in order to produce a strong enough magnetic field, we often need to use super-conducting magnets, which means very, very cold temperatures.

The conflict is that we need to maintain pressure and ultra high temperature in close proximity to super-cold temperatures. We just have not been able to accomplish that other than in very, very tiny experiments, with monstrously large machines.

Work is ongoing in various labs to attempt this, but I am going to guess that, without the benefit of some stupendous discovery, we are at least 50 or 100 years away from being able to sustain a controlled fusion reaction in a size sufficient to generate commercial power.

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What is nuclear fusion?

Answer 1 Fusion, in general, is the joining of light atomic nuclei to form heavier ones. They don't generate heat, but actually, need the energy to occur. These are endothermic reactions, so when a star has turned most of its fuel into iron, it undergoes a dynamic change. The star has lived its life up to now in equilibrium. The gravity that would pull it all together is balanced against the outward force of the energy liberated during exothermic fusion. At some point, the star will collapse. If a star is of insufficient magnitude, the collapse will signal that the star is in its last stages of life. But in stars of sufficient magnitude, there will be much more drama.

The collapse of sufficiently massive stars at the end of their iron forming stages will cause a supernova. Gravity is reclaiming the material, but it is also heating it during the collapse. This extra energy supplies sufficient heat for the fusion reactions that create elements heavier than iron up through uranium. These heavier elements are present on the earth, and they can have only come from a supernova event. The fusion reactions that create these heavy elements have tapped the heat energy created when the star collapsed.

The fusion process is detailed in a number of places. You'll find links below to investigate further.

Nuclear fusion is when two atoms fuse together to create a different atom. This can only occur under extreme conditions such as the conditions in the sun and many stars in our universe. The most common example of nuclear fusion is when two types of (known as isotopes of) hydrogen fuse together to create helium. The isotopes of hydrogen deuterium and tritium fuse to create helium. Deuterium contains one proton and one neutron and tritium contains two neutrons and one proton. Helium contains two protons and two neutrons so it takes the two protons it needs and the two neutrons it needs and spits out one neutron which is not needed. Nuclear fusion generates a huge amount of energy because it takes more energy to hold together two atoms then it does to hold together one. So it there is a lot of unneeded energy, which has to be released. Scientists believe that there used to be the only hydrogen in the universe but in the extreme conditions of the big bang, atoms fused together to create the atoms which are found in the universe today.

Answer 2 (A brief answer)Nuclear fusion is the merging of two light nuclei into one heavier nucleus. The resulting component total mass is less than the masses of the input nuclei. This mass defect changes into energy according to the mass-energy relation of Einstein (E=Mc2 ); E is the energy, M is the mass defect, c is the light speed. The joining of nuclei

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The part of the sun where nuclear fusion occurs?

In the center. Heat then flows out to the outer surface by radiation and convection

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What is the difference between nuclear fusion and nuclear fission?

Difference between fusion and fission

Nuclear fusion is taking two atoms and combining them in to one atom, while nuclear fission takes one atom and splits it into two atoms.

Both reactions involve the nucleus of an atom, and in both reactions, lots and lots of energy are released. Other than that, the two reactions are pretty much opposite. Fission involves the splitting of an atomic nucleus. Fusion involves the fusing of two or more units to create a new, heavier nucleus.

Links are provided to articles on both subjects that have been posted by our friends at Wikipedia, where knowledge is free.

In nuclear fusion two lighter nuclides fuse (join together) to form a heavier nuclide.

In nuclear fission one heavy nuclide splits into two smaller ones. These two are not necessarily identical.

Nuclear fission releases energy only if the resulting nuclides are as heavy as or heavier than Iron40.

Fusion releases energy only if the resulting nuclide is as light as or lighter than Iron40.

It is possible to make elements heavier than Iron40 by fusion, but these reactions are strongly endothermic ( which means that a great deal of energy must be supplied from an external source). This can be done in an accelerator, but the process takes place in any quantity only in an exploding star.

Nuclear fission is when a large nucleus such as uranium or plutonium splits into two smaller nuclei. When Uranium with an atomic mass of 235 absorbs a neutron and becomes Uranium 236 (its critical mass) it splits into two nuclei releasing loads of energy.

Nuclear fusion is when two small nuclei (smaller the iron) fuse together to make a bigger one. The high energies and pressures are needed are very hard to recreate on earth because if you think about it the sun is hot because nuclear fusion is happening inside so we have to create the sun on earth. The only place fusion can happen naturally in stars. Fusion releases even more energy than fission. Most fusion happens between two hydrogen atoms to make a helium atom.

Deuterium is hydrogen with one proton and one neutron (normal hydrogen is 1 proton only). Tritium is Hydrogen with two neutrons and one proton. These particles are what form hydrogen. If you add up the number of particles you will notice that one neutron is left over in the making of helium. This is turned into the massive amount of energy released in a fussion reaction and relased as light but mostly heat.

Nuclear fision is the splitting of atoms and fusion is the combining of atoms

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Nuclear fusion occurs when nuclei?

Nuclear fusion occurs when nuclei are pressed (fused) together so closely that the strong atomic force takes over and causes protons to attract one another, forming new atoms of different types. In order for this to occur, the nuclei must be superheated so as to be fully ionized, i.e. have all of its electrons removed, so they won't interfere. Then, great pressure has to be brought to bear in order to overcome the repulsive effect of the electromagnetic force, allowing the strong interaction to take over.

This is "easy" in the Sun - gravity does all the work - but on Earth, we have not been able to achieve a sustained, controlled fusion reaction to date, because of the problem of containment. - No container is able to hold the superhot, superdense plasma necessary for the fusion reaction to take place. Efforts are underway to use magnetic containment, in the ITER, but that is still highly experimental.

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How is nuclear fission different from nuclear fusion?

Fastern your seatbelt. We've got some ground to cover. But it won't be too difficult to grasp the fundamentals. In either fission or fussion, we are taking about nuclear processes, i.e., the physics of nuclear structure and construction/destruction of that nucleus. The big difference is fusion is the "building" of atomic nuclei, and fission is the "breaking" or "splitting" of atomic nuclei. Fusion is the bonding of atomic nuclei or nuclear particles (nucleons - protons and neutrons) to make "bigger" or "heavier" atomic nuclei. Fission, on the other hand is the splitting of the atom. As the atoms fuse or split they release energy. Lots of it. And most of it is heat energy. In nuclear weapons, the energy is released "all at once" to create a blast. If the energy is released in a "controlled" way, we can release heat at a "useable" rate and apply it to boiling water to make steam. In fusion, protons or neutrons or the nuclei of atoms are forced together and are fused to make a new atomic nucleus. The release of lots and lots of energy accompanies this reaction. That's what powers stars. Currently we can't really do any fusion reactions to make useful power. There are a few agencies working on fusion devices, but the high temperatures required to attain fusion require very special materials and controls. The current "state of the art" fusion facility is the International Thermonuclear Experimental Reactor (and a link is provided). Fusion is unlikely to become a useful source of power for many years. But what about fission? Nuclear fission involves the splitting of large atoms, usually uranium (or sometimes plutonium). When large atoms fission they produce two smaller atoms or fission fragments (and a couple of neutrons and lots of energy). The total mass of the products is less than the mass of the original atom. This mass difference is turned into energy in accordance with the Einstein equation E=mc2. Most of the energy appears in the recoil of the fission fragments, and the heat that is generated is considerable. It is that heat that we capture to turn water into steam to generate electricity. Nuclear Fission: Basics When a nucleus fissions, it splits into several smaller fragments. These fragments, or fission products, are about equal to half the original mass. Two or three neutrons are also emitted. Nuclear Fission The sum of the masses of these fragments is less than the original mass. This 'missing' mass (about 0.1 percent of the original mass) has been converted into energy according to Einstein's equation. Fission can occur when a nucleus of a heavy atom captures a neutron, or it can happen spontaneously. = Nuclear Fusion = Nuclear Fusion Nuclear energy can also be released by fusion of two light elements (elements with low atomic numbers). The power that fuels the sun and the stars is nuclear fusion. In a hydrogen bomb, two isotopes of hydrogen, deuterium and tritium are fused to form a nucleus of helium and a neutron. This fusion releases 17.6 MeV of energy. Unlike nuclear fission, there is no limit on the amount of the fusion that can occur.

Nuclear fusion is taking two different atoms and combining them in to one atom, while nuclear fission takes one atom and seperates it into two atoms. Fission and fusion Fission is splitting the atom, and fusion is combining two or more atoms into one atom.

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Can you use nuclear fusion to make gold?

As a matter of fact, yes you can! But it's not profitable in any way.

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The Sun
Nuclear Fusion

Where do hydrogen nuclei fuse to form a helium nucleus?

This type of fusion reaction is common in the Sun. This is also the type of reaction present when a Hydrogen Bomb explodes.

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Nuclear Fusion

Is nuclear fusion a chemical or nuclear reaction?

Nuclear fusion is a nuclear reaction, not a chemical reaction.

In nuclear fusion, the nuclei of atoms combine in order to form new atoms (hence the term nuclear reaction). This type of reaction is mainly concerned with the movement of protons and neutrons. This is opposed to chemical reactions, which are mainly concerned with the interaction of electrons - the atoms remain of the same element, and the atomic nuclei are unchanged.

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Why dont we use nuclear fusion in nuclear power plants?

Because no one has been able to produce a continuous fusion reaction so far.

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Are all fusion reactions exothermic?

No, fusion of atoms larger than nickel and iron are endothermic and can only occur in supernova explosions.

Also fusion of 2 helium atoms is energetically impossible and just results in various isotopes of hydrogen. To get exothermic helium fusion you need 3 helium atoms, which requires very very high temperature and pressure and produces carbon.

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Does nuclear fusion happen in the convection zone?

no

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How is nuclear energy formed?

Some nuclei, notably U235 and Pu239, can be made to cause a chain reaction where neutrons are produced in nuclear fission, and propogate more subsequent neutrons so that a steady rate of fissions can be achieved. Each fission releases an amount of energy in the form of heat, which is then used in generating plant similar to that in a fossil fuelled power plant.

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Stars
Nuclear Fusion

What is a nuclear equation that shows the overall fusion cycle of the sun?

Nuclear fusion in sun is followed by proton proton chain reaction

during this reaction hydrogen fused to form helium

the main products of this reaction according to nuclear equation is - positron, neutrino, gamma ray photons, isotopes of hydrogen and helium

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How are Nuclear Fission and Nuclear Fusion similar to and different from each other?

Nuclear fission and nuclear fusion are similar in that they both involve changes in the nucleus of the atom. Another similarity is that relatively high energies (for the size of the matter involved) are associated with those nuclear changes.

In general, nuclear fission is the "splitting" of the nucleus of an atom, and nuclear fusion is the fusing or combining of two smaller atomic nuclei to form a larger one. Both nuclear fission and nuclear fusion are described in related questions, which are linked below.

It should be noted that fission results in the release of energy. Fusion, however, can result in the release of energy, or it could require energy to occur. Fusing lighter atomic nuclei to form heavier ones releases energy up to the formation of an iron nucleus. Heavier nuclei beyond iron require energy to be put into the fusion event for it to occur.
Both reactions involve the nucleus of an atom, and in both reactions, lots and lots of excess nuclear binding energy is released. Other than that, the two reactions are pretty much opposite. Fission involves the splitting of an atomic nucleus. Fusion involves the fusing of two or more smaller units to create a new, heavier nucleus.

Links are provided to articles on both subjects that have been posted by our friends at Wikipedia, where knowledge is free.

The similarity between nuclear fission and nuclear fuision is that they both produce huge amount of energy. These could be used to generate electricity, but scientists find it difficult to produce nuclear fusion reactions under conditions that can be safely managed as the temperatures are extremely high (around 150 million degrees Celcius). Fusion is the reaction that occurs in the sun while fission is a process that can be induced and is the splitting of a uranium (or other fissionable) atom into other lighter elements. Fission also releases a lot of usable energy.

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Why is nuclear fusion a nonrenewable energy source?

Fusion combines atoms together to form energy and generates heavier elements. As you continue to form heavier elements you eventually you form iron. Fusing iron together requires more energy than it releases. So once iron is formed fusion is over.

In a star its supernova time.

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Stars are born when gravity pulls gas and dust together with enough pressure to ignite nuclear fusion?

true

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The Difference Between
Nuclear Fission
Nuclear Fusion

What is the difference between fission and fusion?

Fusion refers to the connection or joining of two or more distinct things or bodies while Fission is a splitting of something into two or more parts.

Nuclear fission is the division of a heavy atomic nucleus into two fragments of roughly equal mass, accompanied by the release of a large amount of energy, the binding energy of the subatomic particles.

Nuclear fusion is the joining of two nuclei of light elements to form heavier ones, releasing huge amounts of energy.


Fusion is when multiple nuclei are combined to form a heavier nucleus. For example, the fusion of 2 H atoms into a He atom.

Fission is when one nucleus splits into multiple smaller nuclei. For example, when Uranium 235 splits into Ba and Kr nuclei.

Fusion is the process that produces heat in stars, like the sun. It is safer and cleaner than fission, but we do not currently have the technology required to harness it, and Hydrogen is difficult to obtain on Earth.

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In what part of the sun does nuclear fusion take place?

core

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What is nuclear energy?

Nuclear energy is the energy in the nucleus, or core, of an atom. Atoms are tiny units that make up all matter in the universe. Energy is what holds the nucleus together. There is a huge amount of power in an atom's dense nucleus. Nuclear energy is seen when nuclear fusions or fissions happen.

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