What is Fusion reaction: Definition and 28 Discussions

Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles (neutrons or protons). The difference in mass between the reactants and products is manifested as either the release or the absorption of energy. This difference in mass arises due to the difference in atomic binding energy between the nuclei before and after the reaction. Fusion is the process that powers active or main sequence stars and other high-magnitude stars, where large amounts of energy are released.
A fusion process that produces nuclei lighter than iron-56 or nickel-62 will generally release energy. These elements have relatively small mass per nucleon and large binding energy per nucleon. Fusion of nuclei lighter than these releases energy (an exothermic process), while fusion of heavier nuclei results in energy retained by the product nucleons, and the resulting reaction is endothermic. The opposite is true for the reverse process, nuclear fission. This means that the lighter elements, such as hydrogen and helium, are in general more fusible; while the heavier elements, such as uranium, thorium and plutonium, are more fissionable. The extreme astrophysical event of a supernova can produce enough energy to fuse nuclei into elements heavier than iron.
In 1920, Arthur Eddington suggested hydrogen-helium fusion could be the primary source of stellar energy. Quantum tunneling was discovered by Friedrich Hund in 1929, and shortly afterwards Robert Atkinson and Fritz Houtermans used the measured masses of light elements to show that large amounts of energy could be released by fusing small nuclei. Building on the early experiments in artificial nuclear transmutation by Patrick Blackett, laboratory fusion of hydrogen isotopes was accomplished by Mark Oliphant in 1932. In the remainder of that decade, the theory of the main cycle of nuclear fusion in stars was worked out by Hans Bethe. Research into fusion for military purposes began in the early 1940s as part of the Manhattan Project. Self-sustaining nuclear fusion was first carried out on 1 November 1952, in the Ivy Mike hydrogen (thermonuclear) bomb test.
Research into developing controlled fusion inside fusion reactors has been ongoing since the 1940s, but the technology is still in its development phase.

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  1. C

    B Can this fusion cycle work in practice?

    Hello I would like to ask here because I couldn't find an answer anywhere on the internet. I recently noticed that two fusion equations have a very good reciprocal cycle, namely the equation: 1H + 2H = 3He, and the equation 3He + 2H = 4He + 1H. I understand that it may have practical...
  2. jedishrfu

    Confirmation of Laser Fusion Break Even Point

  3. D

    Nuclear fusion energy calculations

    Me again! For a sci-fi story I'm working on, I've created a sci-fi technology called an Aneutronic Triple Alpha Fusion Reactor. It works via aneutronic fusion, in this case, fusing Deuterium with Helium 3, but it also mimics the triple alpha process found within stars to maximise fuel use...
  4. Leo Liu

    How does D-T fusion reaction utilize its waste to create more fuel?

    In Britannica's article on nuclear fusion, I came across the following description of the recycle of triton and neutrons: What puzzle me are why the tritons are produced from the D-T fusion reaction, given that the products are alpha particle, neutron, and energy; and how the neutrons can be...
  5. TechmoUnity

    B Assistance finding the nuclear energy difference during nuclear fusion

    Hello! I have finished high school quite a few years ago. I did a physics course that went over nuclear fusion and fission, and I quite enjoyed it. However, I unfortunately no longer have those textbooks (I sold them on as many people do). Now I am doing a bit of programming in the field of...
  6. C

    I Can a fusion reaction propagate in a cappilary?

    Can fusion reaction propagate inside a (very thick walled) cappilary if fusion has been initiated at one end? In this situation it seems like all the energy would have nowhere to go but into heating and pressurizing the fuel, providing conditions for further reaction. I imagine this is a...
  7. M

    B Released energy by fusion reaction

    Video Link According to the video in the link above the binding energy for deuterium is about 2 MeV and the binding energy for tritium is about 8 MeV so the total for the input items is 10 MeV the binding energy for helium is 28 MeV I am confused by this part if the resulting binding energy is...
  8. Humbleness

    Calculating total amount of energy in a fusion reaction

    Homework Statement In the following fusion reaction, a deuterium nucleus (D) combines with a tritium nucleus (T) to form a helium nucleus (He-4). If the following masses of deuterium and tritium are used to produce energy, calculate the total amount of energy produced. Homework Equations E =...
  9. S

    I Do stars have any lower mass limit?

    Just read an article about a discovery of the smallest/least massive star in the Milky Way galaxy. The star has 85 times the mass of Jupiter and is known as EBLM J0555-57Ab located about 600 light-years from Earth. The entire article here -...
  10. Jasiu

    I Fusion reaction deuteron + tritium

    Hello. Where is come from the heat (about 17,59MeV) from reaction deuteron + tritium -> Alfa + netron + Q although sum of substrates's mass is greater than sum of products's mass?
  11. H

    Question regarding fusion reaction containment and procedure

    Good evening, I am new to this forum and do not have a strong physics background. So if my questions seem woefully inept please respond with a simple laymans answer. I understand that there are 2 basic ideas for fusion containment, and that the main 2 components of any successful fusion...
  12. I

    Is the use of materials to confine nuclear fusion ruled out?

    Usually people talk about magnetic confinement schemes or some such thing for fusion reactions presumably because the pressure and temperatures would vaporize/destroy all conceived material vessels too quickly. I would like to hear someone talk about the limits of materials in this realm. So...
  13. L

    Binding energy and favorable reactions

    [Moderator note: Thread moved from technical section, thus no template is shown] Hi everyone! I'm currently learning nuclear physics and I have a question: Watching the binding energy per nucleon curve, is the following reaction energetically favorable? 2H + 4He -> 6Li And why? Thanks!
  14. J

    Determining the Probability of a Nuclear Fusion Reaction: Solve Here!

    Homework Statement In a particular nuclear reaction, a neutron moving at 3.6×105ms−1 has a 70% chance of initiating a nuclear fusion reaction. Which of the following options is a possible probability of a neutron moving at 2.2×105ms−1 initiating the same nuclear reaction? I wouldn't be asking...
  15. S

    Direct energy conversion from p+Li-7 fusion reaction?

    I have a question about direct energy conversion; if I want to directly extract electrical energy from the fusion reaction p+Li-7 reaction which generates He nuclei, with a kinetic energy of 8 MeV, what is the most suitable method of doing that? Should some method with charge separation be used...
  16. Warpspeed13

    What type of fusion reaction generates the most neutrons?

    What type of fusion reaction generates the most neutrons? All I've been able to find information for is D-D fusion and D-T fusion.
  17. E

    Mass lost in a single fusion reaction

    How much mass is lost in a single D + T= 4He fusion reaction? And is all of the mass lost converted to energy or just some? The mass lost can be converted to energy using e=mc2.
  18. B

    How Do you Calculate how many x rays are coming off a fusion reaction?

    Hello, I'm trying to figure out how to calculate how much energy is being released in a nuclear fusion reaction from x rays. I think it will have to do with how much deuterium is in the vacuum chamber, how many volts I am using and the amount of resistance of the mesh the electricity is...
  19. F

    Producing fusion reaction with x rays?

    Would it be possible to produce a fusion reaction(fusing deterium atoms) using x rays instead of high voltages? Scientist are trying to create fusion using laser, which is just focused photons, but if you have energetic photons such as x rays, which would knock the electron of the deterium atom...
  20. A

    Fusion Reaction of Hydrogen and Deuterium into Helium

    Homework Statement In a fusion reaction, the nuclei of two atoms join to form a single atom of a different element. In such a reaction, a fraction of the rest energy of the original atoms is converted to kinetic energy of the reaction products. A fusion reaction that occurs in the Sun converts...
  21. A

    Control Fusion Reaction: Difficulties & Possibilities

    why it is so difficult for scientist to control the fusion reaction why they not make a lage room with heat resistance walls and make a explosion to start the fusion reaction and add appropiate amount of hydogen by some hole if small quantity of hydrogen is entered in such room so the...
  22. D

    Fusion reaction energy and columb barrier

    I'm currently studying Freidberg's plasma physics and fusion energy book, I've heard that Fusion between Deutrium and tritium is most suitable for a fusion reactor and how columb barrier plays its role....my question is what happens when two neutrons fuse together? do they face columb collision?
  23. T

    Fusion reaction (don't know what I'm doing wrong)

    Homework Statement In a fusion reaction, the nuclei of two atoms join to form a single atom of a different element. In such a reaction, a fraction of the rest energy of the original atoms is converted to kinetic energy of the reaction products. A fusion reaction that occurs in the Sun converts...
  24. D

    Will nuking jupiter start a helium/hydrogen fusion reaction?

    ala the sun? Jupiter's upper atmosphere is composed of about 88–92% hydrogen and 8–12% helium http://en.wikipedia.org/wiki/Jupiter considering many nuclear weapons have a fusion stage would the explosion propogate? what would rain on my parade?
  25. S

    Fusion Reaction: Kinetic Energy Gain & Energy Source

    In a fusion reaction, the nuclei of two atoms join to form a single atom of a different element. In such a reaction, a fraction of the rest energy of the original atoms is converted to kinetic energy of the reaction products. A fusion reaction that occurs in the Sun converts hydrogen to helium...
  26. C

    Conservation of Energy fusion reaction

    Homework Statement Consider the following fusion reaction 2H+3H →4He + n in which deuterium and tritium fuse together to form a stable isotope of helium plus a neutron. In all of physics, we see experimental confirmation of Conservation of Energy, in which the total amount of energy in a closed...
  27. J

    Fusion Reaction really long problem

    Homework Statement One of the thermonuclear or fusion reactions that takes place inside a star such as our Sun is the production of helium-3 (3He, with two protons and one neutron) and a gamma ray (high-energy photon, denoted by the lowercase Greek letter gamma, ) in a collision between a...
  28. A

    How Is Kinetic Energy Transformed in Nuclear Fusion Reactions?

    Homework Statement In a fusion reaction, the nuclei of two atoms join to form a single atom of a different element. In such a reaction, a fraction of the rest energy of the original atoms is converted to kinetic energy of the reaction products. A fusion reaction that occurs in the Sun converts...