Questions tagged [fusion]
The fusion tag is used for questions about nuclear fusion, both the basic process at a physical level and it's use as a potential energy source.
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What is the heaviest element being produced in Sun?
Helium is being produced currently in Sun. 3 questions.
Other than Helium what other elements are currently being produced in Sun right now.?
Looks like in 5 billion years, when Sun will become a ...
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How hot plasma should be for the nuclear fusion?
Regularly we can read success stories like "physicists obtained
a 100 million Celsius plasma and hold it for 102 seconds".(these are recent data from EAST tokamak)
But what are their aims? ...
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17 views
What defines Fusion-Evaporation Reactions in Nuclear Physics?
A bit of a general question I know; but I would like to understand a bit more about the topic.
The situation is an alpha beam is incident on an Aluminium-27 target, which ejects a neutron and leaves a ...
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1answer
42 views
Is Proton-Tritium fusion possible?
Suppose we have a single tritium nucleus ( $^3_1H$ so two neutrons and one proton). Tritium is a highly unstable nucleic configuration and hence decays into $^3_2He$ with a half life of roughly 12 ...
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What is 'negative' magnetic shear? (plasma physics, magnetohydrodynamics, fusion)
While studying plasma physics, and fusion reactor design, I have repeatedly come across 'magnetic shear', simple enough and explained in some depth.
But, then, there will sometimes be a brief mention ...
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51 views
Can we create new elements or make old elements using nuclear fusion and fission [closed]
Is it possible to use nuclear fusion and fission to create new elements? For example, if you have a carbon dioxide molecule, break the bond between carbon and oxygen, and use nuclear fusion/fission to ...
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1answer
110 views
Is there any difference between the words 'fusion' and 'melting '?
My physics text says this:
'The change of state from solid to liquid is called melting and from liquid to solid is called fusion'.
But according to my chemistry text in a different context,
'The ...
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1answer
51 views
Can we use tritium instead of helium-3 for nuclear fusion reactors?
I know that tritium isn't entirely stable (half-life of about 12.3 years) and might require a lot of energy to create large amounts (and transport/handle safely), but wouldn't that still be easier (...
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3answers
151 views
Why is a nuclear fusion reactor not currently possible? [closed]
Nuclear fission reactors are fairly common, but what technological/physical limitations are currently impeding developing the nuclear fusion reactor? The H-bomb is capable of creating nuclear fusion ...
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1answer
47 views
Are the presense of neutron reflecters the only difference between a hydrogen bomb and a neutron bomb? [closed]
From what I understand, a hydrogen bomb usually has neutron reflectors, like graphite, to increase the yield of the explosion. A neutron bomb does not have those reflectors. Are there any other ...
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15 views
How does increasing the binding energy per nucleon release energy [duplicate]
I don’t get it. if let’s say Uranium undergoes fission to produce Barium and Krypton. Barium and Krypton will have a greater binding energy per nucleon meaning they require more energy to hold the ...
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1answer
50 views
What is the quickest way to stop nuclear fusion without removing the fuel?
Would dumping enormous amounts of liquid nitrogen cool it quickly thus extinguishing it? Could a bomb disperse the fuel preventing fusion? Could adding a material stop the fuel from fusing? Is there ...
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1answer
29 views
How can the products of a higher energy fusion reaction be heavier?
I was told the mass defect of an atom is the difference in mass of the atom versus it's particles, for example:
carbon 12 is less massive than 6 protons + 6 neutrons + 6 electrons.
this negative ...
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2answers
57 views
Which way might commercial fusion power affect the earth's energy balance?
The ITER fusion-energy project might prove the feasibility of commercial fusion-energy generation by mid-century.
This would be a comparatively clean method of energy generation, and subject to ...
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1answer
53 views
If thermonuclear weapons can explode, what's to say a fusion reactor won't? [closed]
They are fundamentally the same reaction. People say that if something goes wrong plasma will expand and cool, not explode. However, what's to say when we achieve q>1 it won't explode? If it won't, ...
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23 views
How is the fusion reaction rate generalized in Plasma Physics and Fusion Energy by J. Freidberg?
I am trying to understand the final step performed in Jeffrey Freidbergs book Plasma Physics and Fusion Energy (ISBN 978-0-521-73317-5) when generalizing the fusion reaction rate. In equation 3.14 in ...
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23 views
Could Pressure Alone at room temperature be used to confine a Plasma and sustain hydrogen fusion?
I'd like someone more knowledgeable of physics pressure and fusion, to weigh in on my idea for sustaining a plasma using off-the-shelf parts.
The pressure at the core of the sun is 1 trillion Earth ...
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1answer
79 views
Why doesn't nuclear fusion produce radioactive waste?
I'm trying to write a paper arguing for why we should spend more money on nuclear fusion research. I keep reading that "nuclear fusion produces no long lived radioactive waste", but when I ...
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2answers
335 views
How does protium-protium fusion work?
How does protium-protium fusion work? As far as I know, a proton turns into a neutron by emitting a positron. How does that work? Shouldn't a proton be slightly lighter than a neutron? This seems to ...
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32 views
Why do tokamaks need to operate in pulsed mode?
The plasma current is normally induced by a transformer coil in the plasma. A Tokamak therefore does not operate continuously, but in pulsed mode like the transformer.
https://www.ipp.mpg.de/1766212/...
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Do Efimov states contribute to fusion reactions other than the triple-alpha process?
An Efimov state is a three-body quantum state in which each two-body subsystem is unbound, but the system as a whole is bound because of the large s-wave scattering length. Intuitively, one can ...
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19 views
Why aren't Flux Compression Generators used in ICF or Z-Pinch experiments?
Inertial confinement fusion requires high pulsed power concentrated in a small area. This can be done with lasers, or it can be done with a Z-Pinch, which converts pulsed electricity into pulsed x-...
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44 views
Why do helium fuse in the Sun?
Initially there are lots of hydrogen atoms and trace elements in the Sun. Despite insufficient energy for the hydrogen to fuse in the core, quantum tunneling saved the day and invoke proton-proton ...
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2answers
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What is the relationship between binding energy, energy released, and mass defect? [duplicate]
Im learning about fission/fusion and cant get mass defect, binding energy, and energy released to fit together in my head.
The three are all equal in magnitude if I understand it correctly?
When, for ...
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1answer
30 views
Speculative: What would happen if towers with supermagnets would be built around an experimental tokamak?
It is a speculative question from an amateur. I am interested in an expert reply carved-out for a non-expert
As I'm avidly observing ITER developments and I'm a great fan of the project (as a child I ...
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On Nucleus-Nucleus potential for fusion reaction of light nuclei
Its know that in nuclear fusion reactions, the nucleus-nucleus potential cannot be simply given by;
$V(r)=\frac{kZ_pZ_t}{r} for, r>\frac{kZ_pZ_t}{E}$
$V(r)=-U_0 , or, \frac{-U_0}{1+e^{\frac{a-r}{b}...
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12 views
Is the 300 second sustained fusion goal set by KSTAR a threshold for net positive energy product of fusion?
KSTAR recently broke a record in fusion technology by maintaining its heat for 20 seconds with a stated goalof reaching 300 seconds.
Why 300? Does 300 get us to the point of net positive energy ...
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45 views
What's wrong with using protium catalytically in a fusion reactor?
P-D fusion results in 3He, then D-3He results in a P+D+D turning into P+4He. Isn't that net energy positive at a relatively low temperature without too many neutrons? Some D+D side products will ...
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1answer
32 views
Radiative Heat Transfer In Nuclear Fusion
Given the extremely high plasma temperatures that are required to sustain a nuclear fusion reaction in a device such as a tokamak reactor, how can such high temperatures be maintained in the presence ...
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3answers
43 views
Another way for production of positive fusion
I am wondering why energy positive fusion cannot be produced in the following manner.
Large tank of hydrogen pressurized to such a high a level it would push the limits of current technology.
...
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1answer
93 views
How much of ITER Tokamak's input power could be eliminated in a future commercial fusion reactor? [closed]
The ITER Tokamak is designed to produce 500 MW of thermal output from 330 MW of input power, ignoring electric conversion efficiency.
The heaters require 150 MW (to heat input plasma by 50 MW), the ...
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Outside grid for fusor
I, for a while now, wanted to build a little Farnsworth desk fusor. Nothing too powerful, simply a small "desk lamp" if you will. As the fusor needs 2 grids, I was wondering, if it might be ...
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1answer
60 views
What would happen if you tried to use oil as fuel in a fusion reactor? [closed]
At first, this question seemed silly, but there might be some sense to it. OpenAI's GPT algorithm suggested to me that using oil in fusion technology could be a breakthrough. I thought about it for ...
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1answer
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I Need the Z-Machine's Circuit Diagram
Where can I find a copy of the circuit diagram for Sandia Lab's Z-Machine, or indeed for any pulse forming network that outperforms the ordinary Marx bank (if such a thing exists)? Google has let me ...
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Is the Marx Bank Still the Gold Standard?
Is the Marx bank still the fastest pulse forming network for generating high magnetic fields at large scale, or is there another design that outperforms it?
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Magnetic Lens Size required to ignite a Fusion burn
What are the dimensions and/or mass of the amount of permanent magnets( NdFeB) required to magnetically focus cosmic rays such that instead of 1 muon per square centimeter per minute hitting the ...
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1answer
42 views
Nuclear reactions in stars: tunneling?
Energy production in stars occurs mainly when a nucleus absorbs a proton or fuses with another nucleus. Some examples:
(i) $\rm{p}(\rm{p},\rm{e}^+\nu)\rm{d}~$ and $~\rm{d}(\rm{p},\gamma)^3\rm{He}~$ ...
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2answers
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Reactivity in nuclear fusion
In nuclear fusion, the graph of reactivity is shown as below.
How can we explain that by increasing the temperature after a certain value, the reactivity decreases?
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1answer
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Can fusors be used to turn Uranium 238 into Plutonium 239?
Since a Farnsworth–Hirsch fusor is apparently a good fast neutron source that is simple enough to build at home, why can't it be used by rogue states or even terrorists to turn non fissile U-238, ...
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3answers
181 views
What if Jupiter or the Sun was made of rock, like Earth and Mars, rather than gas?
Jupiter is a "gas giant". If it was (significantly) bigger the pressure from gravitation would ignite a fusion process and it would become a star, which is basically what happened to the sun....
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23 views
Do we have energy-positive fusion reactors?
This is something I have been wondering about for a long time. I know modern fusion reactors are far from being commercially viable, and probably just as far from going net positive. Still, has there ...
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2answers
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Why does nuclear fusion not occur with nuclei with a nucleon number higher than 56? Please tell me if I am correct
Please tell me if my assumption is correct.
So nuclear fusion does not occur with nuclei (with a nucleon number higher than 56) because the binding energy of the product nucleus is lower than the ...
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0answers
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What is box shape in ion beam drivers for ICF?
What is the meaning of box shape in the ion beam pulses?
i mean in plasma we say the ion beam irradiating the capsule is box shaped. what does it mean?
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1answer
100 views
What is the difference between ion beam and laser?
What is the difference between laser beams and ion beams, especially in inertial confinement fusion?
In inertial fusion, we use lasers as well as ion beams for driving the reaction. What is the ...
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2answers
88 views
Why is hydrogen-boron called a fusion reaction?
As we know, we usually call fusion such a reaction in which two light nuclei make a heavier one and release energy.
For fission, a heavy nucleus breaks into light ones.
My question is, in proton-boron ...
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Are there papers or experiments that point to non-fusion sources of solar neutrinos?
I've read that nuclear fusion is what generates such large quantities of solar neutrinos.
Also saw that it was recently experimentally confirmed that two types/energies of neutrinos are generated in ...
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1answer
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How to calculate the released energy in a fusion reaction knowing the mass of the reactants?
this the reaction formula:$H^2_1 + H^3_1 ->He^4_2 + n^1_0$ (idk how to put the numbers in the left)
and I have the released energy of one reaction $E_r=2,8.10^{-12}J$, How to calculate the released ...
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4answers
322 views
How does the Sun generate its energy?
We all know that the sun generates its energy from nuclear fusion in the core. The electromagnetic radiation produced slowly travels upwards, while constantly being absorbed and re-emitted by the ...
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1answer
77 views
Where is mass defect in nuclear fusion? [duplicate]
The hydrogen is one proton and the helium is two protons and two neutrons. Neutron is a little heavier than the proton. But there is something strange. Where is the mass defection? As a result, the ...
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83 views
Would a highly degenerate cosmic neutrino background affect fusion reactions that proceed via the weak interaction?
This might seem like a really strange question, but here's my reasoning.
A proton-proton fusion reaction proceeds in two steps:
\begin{align*}
p + p + \text{1.25 MeV} &\rightarrow {}^2_2\mathrm{He}...
