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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Does nuclear fusion of light nuclei occur in fire or boiling water?

At the temperature range of ordinary fire or maybe even ordinary boiling water, is the Coulomb potential between light atomic nuclei occasionally overcome to give way to fusion? Basically, how are ...
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Could we use nuclear bombs to generate electricity? [closed]

it seems the biggest problem with fusion power is confinement. on the other hand, we developed a fusion bomb in just a few years. i was wondering if it could be economically viable to use nuclear ...
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Why only light nuclei are able to undergo nuclear fusion not heavy nuclei?

Is it because of the binding energy or the binding energy per nuclei . I am having trouble with this whole binding energy and nuclear fusion concept.
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1answer
148 views

How much energy does proton - carbon 12 fusion produce?

Page 25 of this document from the California Institute of Technology says that proton-carbon 12 fusion releases 7.54 MeV, while Wikipedia says it releases 1.95 MeV. Which one is correct?
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What would keep a hypothetical fusion reactor from “igniting the atmosphere”? [duplicate]

So in the early days of Nuclear fission, there was a concern about the resulting energy igniting the atmosphere in a ball of fire and world-wide death which is awesome terrifying awesomely terrifying. ...
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So how much fuel does a hypothetical fusion plant need?

Reading about potential fusion plants it's easy to get the impression that we have nearly infinite access to the fuels required. But looking aside form how much we have available, I am interested in ...
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1answer
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Why is a stellarator-type nuclear fusion reactor so oddly-shaped?

My first impression: It's a mess. Why is it shaped like that? I can't find any info about its shape other than it's a special arrangement of magnetic coils.
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2answers
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Why did they start Wendelstein 7-X With Helium?

Just saw the first Hydrogen plasma at the Wendelstein reactor. I haven't found anywhere that gives a good explanation as to why they first used a Helium plasma - can anyone shed any light?
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How much iron would result of fusing a human body?

While discussing nonsense plots, a friend and I ran into the question of what would happen to a human enclosed perfectly with an enormous amount of energy, Antimatter or fusion level energy. It was a ...
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Temperature of fusion in the Sun vs. fusion in controlled experiments on Earth

I recently learned that hydrogen fusion (i.e., hydrogen to helium) experiments on Earth have been successful at temperatures in excess of 100,000,000 degrees Celsius. However, I also learned that ...
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2answers
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Is neutron-neutron fusion viable?

Do I get unusual baryon maybe like pentaquark or just a pair of conjoined twin that is very unstable?
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494 views

Why do people say nuclear fusion is 50 years away? [closed]

This '50 years' number is floating around media pretty consistently, even the ITER road map claims that the first commercial reactor will happen post-2050. But why is that? I understand that there is ...
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1answer
344 views

Could atmospheric muons be used to catalyze nuclear fusion?

https://en.wikipedia.org/wiki/Muon-catalyzed_fusion I read above that some work as been done investigating whether muons could be used to catalyze fusion of deuterium and tritium. Apparently they can ...
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Usage of rare earth barium copper oxide (ReBCo) superconductors (for fusion reactors)

Recently, scientist from MIT have proposed a new design for a compact fusion reactor, see for example this ArXiV paper. I do not want to discuss the physics of their reactor but am more interested in ...
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Could anyone explain to me how the products of nuclear fusion/fission are predicted? [duplicate]

I have an idea of how quantum mechanics work, but I know too little to understand which products are a result of certain reactions like bombarding a certain atom with neutrons or just by natural decay....
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1answer
80 views

Can a spheromak propagate in vacuum?

I recently learned about (and am now fascinated by) spheromaks. I am no expert on plasma physics, but as I understand they are analogous to propagating toroidal vortices (smoke rings), but with plasma ...
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Why can't electrostatically accelerated deuterium beams neutralized by electrons produce net energy fusion? [duplicate]

I was looking through the various nuclear fusion approaches and it struck me that they all suffered from one of two problems. Either they wasted a lot of energy trying to accelerate fusion fuel to the ...
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2answers
749 views

Why does the core of a low mass star contract after reaching electron degeneracy?

I am learning about the lives and deaths of stars with a solar mass of 0.4-2. What I understand is that once the star stops hydrogen fusion after using up all its hydrogen, the star leaves the main ...
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1answer
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Reason why stars do not produce elements heavier than iron

In his book "Origins", Neil deGrasse Tyson says that "if you seek to split iron nuclei apart, you must them with additional energy. On the other hand, if you combine iron atoms they will also absorb ...
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336 views

Fusing Hydrogen with lightning

I've been reading about fusion recently (Specifically Deuterium fusion) and a friend of mine asked me if it was possible to fuse two Deuterium atoms with a lightning strike? Now this question has a ...
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2answers
696 views

In a nuclear reaction, where does the energy go?

Lets say two hydrogen fuse together, where does the energy released go? Is it carried away as momentum imparted on the helium atom? Is it carried away in neutrinos? Is it carried away as gamma rays? ...
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1answer
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Mass loss for Fusion energy? [closed]

I am thinking how you can estimate the mass loss of the fusion energy for 1 kWh. I think you cannot use Einstein's $E=mc^2$ to calculate the mass loss in the fusion reaction of the Sun. How can you ...
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1answer
246 views

In what ways does the sun output energy?

I'm curious about the energy output of the sun, and how it breaks down. What fraction is from EM radiation, solar wind, neutrinos, et cetera? How does energy output vary over the EM spectrum? I was ...
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1answer
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Using nuclear devices to terraform Mars: Elon Musk's nuclear proposal? [closed]

Elon Musk has recently suggested Using nuclear devices to terraform Mars. In the past, comet related ideas were mooted, but Musk seems, to me anyway, to be a man in a hurry and perhaps his idea has ...
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1answer
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How does fusion work in the Sun if neutrons have more mass than protons?

According to my textbook, the next result of the fusion reactions in the Sun is: 4H -> He + neutrinos + gamma photons However, if hydrogen atoms are basically a proton and helium atoms are 2 protons ...
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566 views

How can the magnetic field of a tokamak or stellatron hold against the outwards plasma pressure?

I understand that magnetic containment structures like tokamaks generate a toroidal magnetic field in which the plasma particles move in helices around the field lines, because of the Lorentz force. A ...
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Are known (“old”) elements being made synthetically using fusion?

Are known ("old") elements being made synthetically using fusion? I hear about research about making new heavy elements, but type "making known elements" on Google and nothing comes up. Are any known ...
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What happens to Hydrogen-Boron plasma at 3 billion Kelvin?

A recent popular report states (beware, I believe it is not peer reviewed and this slightly smells like a PR stunt) that a private company TriAlpha has made some notable progress towards Hydrogen-...
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What causes the death of the Sun?

In a previous question I learned that in each second only a miniscule portion of the total hydrogen in the Sun is converted to helium and that the number is 1/10^18 of its mass converted each second. ...
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252 views

Where is the Hydrogen the Sun consumes?

I understand the Sun consumes 600,000,000 tons of Hydrogen each second. Where is this Hydrogen? Is all the Hydrogen the Sun will ever consume inside it or are there vast amounts of Hydrogen in space ...
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4answers
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Why do stars undergo nuclear fusion?

This might sound silly. But we always talk about nuclear fusion in stars and I have always wondered why this process happens at all. Is it inevitable for fusion to happen at the temperature and ...
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Why didn't the Big Bang create heavy elements?

In the case of a supernova explosion it is possible to create heavy elements through fusion. Supernovae have a tremendous amount of energy in a very small volume but not as much energy per volume as ...
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1answer
152 views

Can the lithium test be applied to differentiate brown dwarfs from other substellar objects?

The lithium test is often used to differentiate brown dwarfs from low-mass M-type dwarfs (see e.g. Martin et al. (1994)), because brown dwarfs (at least the lower-mass ones) do not burn lithium, ...
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1answer
809 views

Do supernovae produce an appreciable amount of lithium?

David Z's answer to this question got me wondering - is any appreciable amount of lithium produced as the result of a supernova explosion, either by fusion (which seems unlikely to me, but I don't ...
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848 views

How is hydrogen stored in hydrogen bombs?

Fusion bombs obviously fuse hydrogen atoms, using the pressure from a fission bomb. But how much hydrogen does it contain, and how is it stored? AFAIK hydrogen easily drops its electron and escapes as ...
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2answers
639 views

How much energy is released per unit mass from depressurizing degenerate matter?

A neutron star remnant consists mostly of neutron degenerate matter. If you happened to suddenly have 1 kg of it in your lap without the pressure necessary to keep it degenerate, I suppose it would "...
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849 views

Can/will antimatter ever be superior to fusion as a practical electricity source?

I was reading the top answer on this page and I didn't quite understand if the author (presuming the answer is correct) meant a) that fusion was always better, or b) that once we figure out fusion we ...
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2answers
149 views

Help identifying a Fusion approach

Several years ago, I saw a Google video (back before the YouTube acquisition) where the leader of a group studying an unusual approach to fusion gave a presentation. His approach centered on a ...
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1answer
193 views

Why do practical fusion reactions need more than one product?

The Wikipedia article about nuclear fusion says that To be a useful energy source, a fusion reaction must ... have two or more products: This allows simultaneous conservation of energy and momentum ...
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3answers
1k views

Pure hydrogen star

What is the smallest mass of pure hydrogen that can ignite fusion? That is can population III stars have tiny masses? How would such stars develop? How long would such a star last?
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1answer
1k views

Using particle accelerators for nuclear fusion [duplicate]

Apologies this is probably a stupid idea but I am curious and my knowledge of physics is limited as I am 14. So I was wondering if we could use particle accelerators to achieve nuclear fusion. I have ...
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1answer
48 views

Plot of fusion energy output growth? [closed]

What would a chart of energy output of elements of mass X fused with hydrogen look like? What about X fused with X?
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596 views

Free neutrons in the sun's core?

In the standard description of proton-proton fusion, the first step of the interaction proceeds through the unbound diproton $\rm^2He$: $$ \begin{aligned} \rm p + p &\to \rm {}^2He^* \\ \rm ^2He^* ...
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3answers
843 views

Coupling fission and fusion and disappear all mass. Why doesn't this happen?

I'm confused about the fact that in a fission process the masses of the "products" are less than the mass of the "reactants". And in a fusion process the masses of the "products" are less than the ...
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311 views

If planet like Jupiter is massive enough to hold hydrogen with its gravity is it bound to become a star?

I have been reading about Jupiter as of late and reason I am asking is if Jupiter has strong enough gravity to pull hydrogen to itself then it should be only matter of time when it will acquire enough ...
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Difference between fusion plasma and fluorescent lamp plasmas

How is the plasma in a compact fluorescent lamp (CFL) different from a plasma in say ITER or the sun? Why does ITER need 100MK and a CFL can work at practically room temperature (apart from the ...
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1answer
327 views

Are fusors a cost-effective source of helium?

It's not hard to imagine geology that didn't give us convenient concentrations of terrestrial helium, or that someday soon we'll have exhausted those natural sources. How cost-effective is existing ...
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Why more Fe-56 than Ni-62 as fusion product in heavy stars?

Suppose we create an Fe-56 nucleus and an Ni-62 nucleus, each from individual protons and neutrons. In the case of Ni-62, more mass per nucleon is converted to binding energy. Thus we could argue the ...
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133 views

Solar Power Fusion

Would it be possible through a clever arrangement of solar dishes, lenses and mirrors etc, to create fusion at the focal point? Imagine you arrange your solar dishes, lenses and mirrors in such a way,...
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292 views

How large should an optically large fusion reactor be?

This is just theoretical consideration. I expect that size of the reactor would be impractical to build on Earth, but I'm interested how much. EDIT: perhaps it could be good for some huge spacecraft ...

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