Fusion Definition and 849 Threads

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. pinochet

    Is Fusion Considered a Chemical Reaction in Stars?

    im reading a chemistry text and its says in daltons law chemicals can not change into atoms during a chemical reaction.but if fusion is a chemical reaction then this is wrong beacuse in stars for example hydrogen combine with hydrogen to form helium .i guest i need a little clarification of...
  2. L

    Supercooled water - latent heat of fusion

    During water solidification at 1 atm, about 80 cal/g of heat are released; since ice specific heat is less than 1 cal/(g °C) it means that if this heat would be totally transferred to the ice, its temperature should increase of more than 80°C. How then it is that very fast solidification from...
  3. Caolan

    Plasma Industry trade journals for plasma fusion

    Hello, as a software engineer I am used to having industry specific trade journals from ACM that discuss Operating systems, genetic algorithms, neural nets, etc. ... Are there any equivalent ones for physics that covers fusion plasma and it's topics such as electromagnetism, superconductivity...
  4. Caolan

    Best subjects to study fusion plasma by.

    Hello, I have been doing software engineering for over 20 years and I feel like it's time for a change before I get too ancient. I have been following and reading about plasma fusion for a number of years now and I would like to study this and be able to do some research in either a Ph.D...
  5. K

    When fusion energy is successful, what happen to other sources of energy?

    Hi, I have a question that might involve politics so I post it here. In the near future when fusion energy become successful, cheap, low-cost, small size, high above break-even point, etc. are there any role left for other alternative energy such as solar, wind, etc? Do we need those...
  6. mesa

    Looking for a boron nitride sheet for thin film dep / Fusion

    Hello fellow PFers. Recently we ran our first fusion experiment on campus by utilizing our IBeAM analysis lab with a BN electrical insulator target after installing and calibrating a gamma detector in the vacuum chamber. The Professor funding the experiment needed to see we could achieve a...
  7. D

    Is this an example of nuclear fusion?

    My physics SATII book states that this is not an example of nuclear fusion: 4/2 He + 27/13 Al ⇒30/15 P +1/0 n If this isn't fusion then what is it? (The top number of the division is the mass; the bottom is the atomic number)
  8. gracy

    Multiple fusion: daughter cells different from parent cell?

    I think in Multiple fusion daughter cells are different from parent cell.I interpreted this by looking at the image below Have I interpreted correctly?Is this image reliable?
  9. T

    How is fusion technology progressing in 2021?

    I am having difficulty finding reliable sources of news and information regarding the status of various methods of attempting to generate energy through fusion, but unfortunately, the information is either outdated, is nothing but rumour and conjecture, or has been... how shall I put it...
  10. M

    What are the risks of fusion and fission power compared to each other?

    I am curious about the relative dangers of fusion and fission power. Obviously fusion is much safer, but it is not without any risk. Radioactive materials are produced, and containment systems can fail. I am wondering if anyone can give a comparison of a fission meltdown vs. a worst-case...
  11. Sebastiaan

    Helium 3 breeding in fusion reactors

    There are several fusion reaction which produce Helium 3 as ash 1) D + D => T + p / He-3 + n 2) p + Li-6 => He-4 + He-3 3) p + D => He-3 + photons Assuming we can create and maintain these fusion reactors. Would it be possible to to collect the Helium3 from the fusion tractor...
  12. D

    Do supersolids or BECs have higher fusion cross sections?

    The Lawson criterion suggests that a chain fusion reaction will only occur in a confined plasma. Since it's a product of temperature and pressure (or density) a chain reaction would be virtually impossible in a cold target at pressures attainable in a lab. Likewise, the Coulomb barrier makes it...
  13. K

    Maximum mass of a metal you can melt; Heat of Transformation

    Homework Statement What is the maximum mass of lead you could melt with 2000 J of heat, starting from 25 ∘C ? Lead melts at 328∘C , its specific heat is 128 J/(kg⋅K) , and its heat of fusion is 2.5×10^4 J/kg . Homework Equations Need to find both the mass in the heat of transformation (Q =...
  14. S

    Are particles lost during fusion?

    Hi simple question here, I was wondering if matter (actual particles) are lost from the fusion process.
  15. S

    Can Lasers Used for Building Molecules Initiate Nuclear Fusion?

    http://www.iflscience.com/space/molecules-have-been-built-using-laser-beam-first-time Is there a way that fusion could be achieved with coherent control like this? If it can build molecules couldn't deuterium-deuterium be achieved?
  16. S

    Nano Fusion? Micro Fusion? Fusion Learning Source?

    When experimenting with fusion, why do we always go so big and make extremely expensive reactors that take years to create and even construct facilities for? I've seen some failed attempts at making fusion happen in carbon nanotubes, failing in the sense that the carbon nanotubes are just...
  17. DHF

    Need help figuring out a possible fusion engine

    Hello, I am in the process of writing space based sci fi novella, I made a few posts last year and earlier this year regarding different aspects of the ship and crew. If anyone is interested, I wanted to concentrate on the fusion engine of the ship itself and hopefully come up with a feasible...
  18. Caolan

    Prerequisites for Plasma Physics and Fusion

    Hello I am looking to pursue a master or Ph.D in plasma physics focusing on fusion tokamak reactors. I have an undergrad in Comp Sci and am starting the necessary physics work to apply to grad school. Besides electromagnetics, are there other areas I should focus on? What are the best websites...
  19. C

    Nuclear fusion using miniature optical particle accelerator?

    Greetings I am not a physicist myself, so please forgive me, if my question/proposition will sound naif. I noticed some articles about accelerating electrons using laser and glass gratings: http://phys.org/news/2013-09-chip.html http://phys.org/news/2013-10-particles-compact-particle.html I...
  20. R

    Can Nuclear Fission and Fusion Power a Bicycle?

    is it possible to create a bike involving nuclear fission and fusion . by using any nuclear reactant.
  21. H

    Binding energy per nucleon and fission/fusion

    Homework Statement Ok so i know that the binding energy per nucleon inceases after fission and fusion and the difference in the binding energy is given out as energy. But if the binding enrgy increases shouldn't there be energy taken in(rather than given out)? Also why is the net loss in my =...
  22. Stephanus

    Fusion Power Economic Impact: An Overview

    Dear PF Forum, Can anyone give an idea. Supposed fusion power is available. With its limitless fuel source from the ocean. What would happen? How much would this energy cost in term of money compared to gasoline and electricity? In fission, the fuel is expensive (uranium).
  23. T

    How many Fusion Power Plants to power humanity?

    I watched that documentary by Dr. Brian Cox about nuclear fusion development and in one segment Dr. Saul Griffith tries to calculate how much would World need renewable power sources like wind farms, solar panels, hydroelectric generators etc. to substitute oil use completely in like 20 years...
  24. 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...
  25. S

    Proton–lithium-7 fusion - energy of the two He nuclei?

    In articles on aneutronic fusion, the reaction Proton–lithium-7 is mentioned as a possibility. Now I wonder; what is the kinetic energy of the 2 He nuclei? How much is gamma rays? Proton–lithium-7 fusion p + 7Li → 4He + 4He + 17.2 MeV
  26. S

    Can I create ITER geometry for MCNP using VISEDX and Notepad?

    Homework Statement the radius from the symmetry to center of the plasma is about 6.2 metres and the minor radius is 2 metres Homework Equations Can you guys help me to make the plasma geometry for MCNP? The Attempt at a Solution the softcode of plasma geometry
  27. Joshua McAnaney

    My Theoretical Fusion Reactor- Looking For Feedback

    Ok, so before I begin, I'd like to point out that I'm a 16-year-old GCSE student from the UK. Therefore all of my physics knowledge above high school level is self-taught, so I am by no means an expert. Anyway, I plan on building a deuterium reactor this Summer as a personal project, and I've...
  28. Stephanus

    Fission or Fusion? Exploring Nuclear Reactions with Li-6

    Dear PF Forum, In previous thread, I am asking about fusion power. But there is one thing that intriguing me. This is one of the reactions that produces tritium. n + _3^6Li -> _2^4He + _1^3H + 4.8 Mev What is this reaction called? 1. Fusion? If yes, why it's called fusion? 2. Fission? 3. Other...
  29. Stephanus

    Fusion Power: Exploring Q Values and Efficiency

    Dear PF Forum, I'd like to know more about fusion power. Perhaps someone can give me idea. 1. Is Q is inefficient, take ITER for example? Supposed Q < 1, can't the produced heat boils water and recycled back to the system to produce fusion again? After all, fusion power plant (if it can be...
  30. Matt atkinson

    Maximum Positron Energy in Proton Fusion and Beta + Decay

    Homework Statement Consider; p+p \rightarrow d + e^+ + \nu_e Assume the binding energy of deuteron is 2.2MeV, calculate the maximum energy that the positron can have. Homework Equations m_p=938.28MeV/c^2 m_n=939.566MeV/c^2 m_d=1875.6MeV/c^2 The Attempt at a Solution Assuming the neutrino was...
  31. golphan

    IMU-Gyro Bandwidth and Sensor Fusion on Performance

    Hello, For my Master's Project, we are to choose an IMU module to stabilize a platform. You can think of a servo actuated turret, mounted on a Stewart Platform(which will generate the disturbances). The angular position error should be very low and there are both high and low frequency...
  32. Dyatlov

    Looking for the complete fusion process inside our Sun.

    Hello. I want to know the full in-detail process which happends inside our Sun's thermo-nuclear core. As far as I know the steps in the H - He fusion process are: 1) H+H -> He2 2) He2 can rarely decay (Beta plus) into Deterium and a positron 3) If so Deterium + H -> He3 4) He3 + He3 -> He4 + 2H...
  33. Teen4Ideas

    Is My Idea Valid? Nuclear Fusion Power

    So as we all know (or at least I assume) Global Warming is real and happening, I am a teen, 17, and not trying to get answers for homework or anything like that. I just want to know, is it possible to create fusion using the temperature found at active Geo-thermal sites to reach the temp...
  34. S

    Find Fusion Cross Sections for All Isotope Pairs - Data/Book/Program/Formula

    Is there a book or database that lists all (or many) pairs of isotopes along with the energy at which they have the higest probability of fusion and what that probability is? Or is there a program that uses models to make a guess given a pair? Or a formula I could use to make the guess myself...
  35. Glenstr

    Opinion on Lockheed Martin's fusion "breakthrough"

    I've been following this with interest, and would like the opinion on those here with a lot more knowledge of the subject than I am. Depending on what you read, this is technology that will be available within a decade, or it's a pipe dream many decades away. Is it something we'll see in our...
  36. 1

    Radiated power of electron in fusion device?

    Homework Statement Some time ago, an (in)famous paper by Trubnikov argued that magnetic fusion would be impossible because the power radiated by electrons would exceed any likely fusion power. He provided a very elaborate calculation, but the result was not greatly diffferent from the simple...
  37. Andropov

    D-shape cross-section of plasma in fusion reactors

    I was curious about why the plasma inside a modern fusion reactor (ITER, DIII-D) is modeled with a D-shaped cross section. From what I've read, it is more stable that way, but WHY is it more stable than a similar plasma flow with a circular cross-section? Thanks in advance (and sorry if I...
  38. T

    How would neutrinos affect fusion?

    How would fusion processes be affected, by a background bath / sea of neutrinos ? Would the constant interactions between fusion products, and neutrinos, constantly break apart the fusion products, and so tend to "undo" the fusion?
  39. Raiden60

    Nuclear Fusion: Why is energy created from mass?

    Ok, so nuclear fusion is given by the formula E=MC2, where E = Energy, M = Rest mass and C = 299792458. To my understanding, this means that if two protons collide under the incredibly high speeds/temperatures(like they do in the sun), they will fuse, having reduced mass and that mass is...
  40. G

    Neutron Flux in ITER: Benefits & Containment Challenges

    I was reading that the ITER will take advantage of the energetic neutron flux by using them and lithium 6 to breed tritium for more fuel, and to use multiple heat exchangers to grab their energy. And just to make sure that I'm reading it right, the main problem with the neutrons will be their...
  41. stephenranger

    Solve Latent Heat of Fusion Homework Problem

    Homework Statement You take a 0.5 L bottle of water (5 °C) from a refrigerator, and pour it into a glass. Find the mass of ice at 0 °C needed to cool your drink down to 1 °C ? the heat of fusion of water is 333 kJ/kg, and the specific heat of water is 4.19 kJ?(kg.°C). Homework EquationsThe...
  42. K

    Is There a Scientific Explanation for the Controversial Concept of Cold Fusion?

    Could somebody explain me if there's a theory, axiom, law or something that can refuse the possibility of "Cold Fusion" in experimental basis? Thanks a lot. Karmo
  43. S

    Latent heat of fusion for water question

    Hello, I am doing some research involving supercooled water flash freezing into ice. I am doing some calculations and I think that I must be wrong judging by my result. Using the latent heat of fusion of water, and the specific heat of water, I can calculate a temperature value which should...
  44. Moriarty

    Fusion and Renewable Energy Education Paths

    My counselors, advisers, and teachers are tired of me so I've come here for some help. I've been interested in renewable energy since I was much younger, but was wondering what kind of path one goes down to dive into becoming a part of the research involved in figuring out our problems with...
  45. Y

    Fusion Power: Exploring ITER and Molten Salt Thorium Reactors

    I would suggest that everyone check out the ITER fusion tokomak project in progress. If this unit works it will change the world. Also Molten salt thorium reactors have gotten a fresh look..Weinberg and Radkowsky s work from the old days may use nuclear waste blend to power no pressurized safer...
  46. J

    Can Negative Temperatures Bring Us Closer to Fusion as a Viable Power Source?

    I was reading about negative temperature here http://www.nature.com/news/quantum-gas-goes-below-absolute-zero-1.12146 and how the state is "hotter than hot" and thought of fusion.Since you need very high temperatures for fusion does the discovery on negative temperatures bring fusion as a power...
  47. J

    Lockheed SkunkWorks Fusion plan

    In the news today, several articles about Lockheed's ambitious five or ten year plan. eg this one from the Washington Post. http://www.washingtonpost.com/news/capital-business/wp/2014/10/15/nuclear-fusion-energy-in-a-decade-lockheed-martin-is-betting-on-it/ This one from Aviation Week...
  48. T

    Neutron Capture in Hydrogen Fusion Reactor

    A recent issue of Aviation Week described a novel design for a fusion reactor from the Lockheed Skunk Works. It was smaller, simpler and lighter than the extant systems now being built and they're optimistic about it's test run in five years. I wrote a letter to the editor touting this departure...
  49. T

    Fusion Due to Gravitation in Bosonic Atoms

    In a bosonic atom i.e. Hydrogen, why do we never observe quantum tunneling past the coulomb barrier leading to multiple atoms occupying the same area of space thus (due to Newton's law of universal gravitation) accelerating towards each other resulting in nuclear fusion?
  50. FuturePhysicist

    Can a Teen Build a Fusion Reactor with a Budget Power Supply?

    Hello, I'm 15 and very interested in physics. I'm building a safe nuclear fusion reactor as a science project. (I know how to safely handle high voltage and radiation) I have a question about the power supply. First off, I know that fusion takes around 40 Kilo-volts and it needs to have a...
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