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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1answer
72 views

How does the $p+p + e^-\rightarrow D + \gamma\gamma+ \nu$ reaction proceed in the sun?

In this video on nuclear fusion the explanation of the reaction $p+p\rightarrow D + \nu + \gamma\gamma$ is that the two protons collide, form a weakly bound state, and then sometimes decay into the ...
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How To Simulate Muon Induced Nuclear Fusion?

I am familiar with euler-lagrange equations which can be used to simulate a mechanical system, something like an inverted pendulum on a cart. How can I simulate a volume of deuterium and tritium with ...
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1answer
31 views

Is relativistic channeled electron catalyzed fusion possible?

A few words first  about muon catalyzed fusion.  You can see this question sigoldberg1 answer, and  this link. "The muon may bump the electron from one of the hydrogen isotopes. The muon, 207 ...
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17 views

NAS report on fast ignition

I'm looking for a paper, or much more likely a small part of a large report, by the National Academy of Sciences from around 2013 on the topic of fusion. The report mentions the fast ignition approach ...
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1answer
59 views

Has proton-proton fusion ever been seriously considered for an artificial fusion reactor?

All contemporary efforts to perform nuclear fusion as a source of power have focused on reactions between isotopes (often deuterium, tritium, or He3) and/or light elements (often boron or lithium ...
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1answer
68 views

Ultra Cold Neutrons in a Bottle Question

If you take a large amount of ultracold neutrons and confine them in a bottle would they then decay into protons and then fuse because they are so tightly condensed that the protons, once neutrons, ...
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2answers
74 views

How do we recover fusion energy from gamma photons

Most fusion reactions create energy in form of hard gamma radiations. A single gamma photon carries energy orders of magnitude higher than any ionization level. Even if we develop some hardcore ...
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1answer
22 views

Tuning Drifts in Tokamaks

If we managed to make over 50 % of the drifting of the guiding centers of the gyrating particles inside a tokamak to occur into the inwards direction, away from the tokamak walls, would that allow us ...
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33 views

Intermediate product of CNO cycle

CNO cycle of stellar nucleosynthesis involves several steps in which different isotopes of Carbon, Nitrogen, and Oxygen are transmuted into each other when hit by a ...
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1answer
23 views

Why doesn't a deuterium-deuterium reaction usually yield Helium-4?

I assume the above reaction is less energetically favorable than the creation of He-3 (plus a neutron) or tritium plus a proton? But why/how? Or are the hard, hot, fast collisions too much for it to ...
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1answer
83 views

Why does fusion above nickel 56 require energy?

I've always struggled with the concept of fission and fusion. I mean I can show a mass deficit with math easily enough but I have always struggled understanding the fundamental concept of why things ...
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Is fission/fusion to iron the most efficient way to convert mass to energy?

Is fission/fusion of any element to iron-56 (or nickel-62?) the best way to convert mass to energy, that doesn't involve black holes? In other words, will we be always limited to convert only about 1%...
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1answer
48 views

Is there a “pinch effect” in a Tokamak?

Is there a "pinch effect" in a Tokamak, like in a linear Z-pinch or in a circular pinch (the ZETA machine from the late 50's)? Tokamaks run in a pulsed mode and a powerful circular current is induced ...
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50 views

How can corium eating its way into water tanks cause a megaton scale explosion? [duplicate]

The 2019 miniseries "Chernobyl" appears to state that the "lava like" substance of melted radioactive matter from the core, the so-called "corium", could eat its way down into the water reservoirs ...
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2answers
100 views

How can Sun burn in space?

If there is no oxygen in space how can sun burn in space. (even though I know fire is caused by nuclear reaction inside sun)
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1answer
62 views

What if a fusion reactor had moving parts?

I have never dug into fusion physics, but from what I gather one of the main problems is confining the fusion in a small region of space for long enough to get enough helium fused to counterbalance ...
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3answers
385 views

Whats the next step after commercial fusion reactors? [closed]

I'm trying to write some science fiction where they've had nuclear fusion working for quite sometime, interplanetary travel is no problem, and they're debating making the next step to a radical new, ...
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33 views

Released energy during fusion reaction

Click to view the video at required time 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 ...
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0answers
62 views

Why is the D+P fusion reaction not considered for large-scale power production?

I know that D+D (fusion of deuterium + deuterium nuclei) as well as D+T (fusion of deuterium and tritium nuclei) are the reactions most commonly considered for large-scale power production. Why not D+...
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3answers
53 views

Binding energy, fission and fusion

My high school physics book doesn't elaborate the idea of binding energy and how it's related to fission and fusion adequately in a way that made me have wrong thoughts about these ideas. What i ...
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2answers
109 views

Explain to me why the following reaction can happen in big stars but not on earth

$$ \rm {}^{12}C +{}^{12}C\rightarrow {}^{20}Ne + {}^4He $$ why doesn't this reaction occur on earth? but occurs in big stars?
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1answer
21 views

How can you determine how much neutron shielding is necessary for a given neutron source?

Trying to make a fusor at home and I was wondering if there is an industry standard or perhaps an equation to determine how and what type of neutron shielding is necessary to protect against the high ...
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0answers
27 views

CNO-cycle in Population III stars [duplicate]

It has been stated several times here and probably elsewhere that the first population III stars were unable to undergo H-to-He fusion via the CNO cycle as there was virtually no carbon-12 at the ...
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1answer
55 views

What is the maximum energy that can be released by thermonuclear device?

Forgive me by posing this somewhat scary question, but it's just out of curiosity I'm asking it. In this video we're witnessing the beautiful and at the same time horrific blast of the tsar bomba, ...
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What is Incoming wave boundary condition (IWBC) in context of nuclear fusion reaction?

For calculation of fusion cross section at sub barrier energies, instead of regular boundary condition we impose Incoming wave boundary condition (IWBC). How does this different from normal boundary ...
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37 views

Sensitivity of latent heat of fusion of ice on temperature and pressure

The enthalpy of fusion is the heat necessary to convert 1 kg of ice to liquid water. According to Wikipedia, this heat equals 333,55 kJ/kg. Does this heat change with the temperature or pressure and ...
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1answer
45 views

Fusion Kinetic Energy

In fusion, the mass of the reactants is greater than the mass of the products. Thus, mass is lost in fusion. My thinking was that this mass defect is converted into binding energy that is then used to ...
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1answer
47 views

If all we need to do is bombard with alpha particles then why can't we do nuclear fusion like that in the star?

In Chadwick's experiment, alpha particle from a source are bombarded on beryllium atom and fusion occurs to produce carbon atoms. My question is that if it is that easy to cause nuclear fusion, then ...
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4answers
171 views

Does the weak force have an attractive/repulsive force observable in everyday life like the other forces?

After the correct comments, this question is not here to compare gravity's and EM's long range forces' energetics and amplitudes to microscopic scattering amplitudes of such forces as weak and strong. ...
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1answer
51 views

If binding energy (from mass defect) is essentially the strong nuclear force maintaining the nucleus, why is it released?

I am aware that during nuclear fusion for light elements and nuclear fission for heavy elements, the resultant elements have less mass than the original reacting elements (ie the mass defect) because ...
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98 views

Why did the Lockheed Martin compact fusion reactor failed? [duplicate]

What made the compact fusion reactor to not be compact. What assumptions did lokheed made in its simulation that showed that it could work. Can we do anything that could make it work or it is ...
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2answers
35 views

Nuclear Feedback Loop (Fusion and Fission)

What are the main factors that prevent a feedback loop being created by using a hybrid method of fission and fusion. Fusion building up to fissionable materials, and fission breaking down till fusion ...
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1answer
33 views

Is quantitative knowledge of the Standard Model useful in the development of controlled fusion?

I have read articles about quantitative knowledge of particle physics, such as energies, cross sections and particle lifetimes, gained from work at the LHC and other accelerators. Is such quantitative ...
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1answer
56 views

Why the National Ignition Facility try to use 192 laser beams to trigger ignition without heat capsule?

In the discussion of the question "Nuclear Fusion with extremely high pressure and low temperature", the conclusion is only ultrahigh pressure cannot trigger fusion. But why does NIF try to use 192 ...
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1answer
58 views

What exactly sets the scale in Fusion power plants?

In fusion power plants, larger devices are said to achieve fusion more easily, next step tokamaks like DEMO are even larger than ITER. In a quantitative way, what exactly isn't scale invariant in a ...
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1answer
62 views

is possible to create a nuclear fusion using simple electric arc discharge?

If we have a simple discharge tube filled by deuterium gas or even heavy water, and put tungsten electrodes close to each other to create a huge electric field, then using a megavolt generator to ...
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1answer
133 views

Where is nuclear fusion occuring in the Sun?

My understanding is that the sun is basically a sphere of hydrogen with a helium core, and that the hydrogen is undergoing nuclear fusion to produce helium. There are many images and cross-sectional ...
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98 views

Discussion about a new nuclear fusion design [duplicate]

Let me clarify here, this is not cold fusion. D&T gas will be compressed very rapidly and its temperature will increase very fast. So, I don't think this is a duplicate question. I have a new ...
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39 views

Magnetic cage for keeping plasma around itself

Let's assume that we have an object in vacuum, venting hydrogen plasma around itself. This object has a powerful internal electrical source, connected to a cage of superconducting wire around it, in ...
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1answer
39 views

Sun's energy and grand unification

According to Wikipedia, The approximate grand unification energy value is equal to $1×10^{25}$ eV or $10^{16}$ GeV This is equal to $1602176$ J. Now, The Earth receives 174 petawatts (PW) ...
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1answer
668 views

Fusion confusion: what did 12 year old Jackson Oswalt do?

This kid has been showing up in news feeds, but only credulous pop media articles, not hard science reporting. What did he build, and what physics does his device do?
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37 views

Proton-Proton, CNO, or white dwarf matter fusion reactor: Is it vaguely possible?

I understand that all efforts at present to make fusion work as an energy source have used light nuclei other than protons due to the fact that the cross section of the proton-proton reaction is just ...
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1answer
45 views

Energy budget of of proton-proton fusion (p-p chain)

How much energy is released in the first nuclear reaction of the p-p chain which produces energy in lower-mass stars like the Sun? The value of 1.44 MeV is given in many sources, but I don't ...
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1answer
34 views

By how much are various dibaryon states unbound?

It has been known for a long time that the deuteron is stable but the dineutron (nn) and diproton (pp) are not. Many textbooks comment on this, but all the ones I found so far do not give quantitative ...
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109 views

How many times do solar protons repeatedly fuse and fission before they form deuteron

In the proton-proton chain reaction in the Sun, the first step is $$p + p \rightarrow \; ^2_2{\rm He} .$$ After this, the most likely thing to happen next is that the reverse reaction occurs: the $^...
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47 views

Can we overcome or mitigate the electrostatic force?

After reading this answer and reading a bit more about fusion, I wondered, is there a way to mitigate the electrostatic force between two nuclei so fusion could take place at lower energies? For ...
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1answer
73 views

Is it 'easier' to fuse heavier elements than light ones?

After reading this answer, I wondered the title question. It seems part of our difficulty in harnessing fusion power is controlling the hydrogen and helium (plasma?) while fusion is taking place, i.e. ...
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15k views

Why do fusion and fission both release energy?

I only have high school physics knowledge, but here is my understanding: Fusion: 2 atoms come together to form a new atom. This process releases the energy keeping them apart, and is very energetic. ...
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2answers
74 views

Do only 'giant stars' fuse large amounts of elements other than hydrogen and helium?

Do only giant stars initiate 'full-on' carbon (and higher element) fusion, even though red giants on the larger end of the spectrum create carbon and oxygen via producing helium per the CNO cycle?
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4answers
109 views

Electronically controlled fusion reactor

It seems that currently, only two types of fusion reactor styles are being used for large scale testing: the Stellarator and the Tokamak. Both of these and a whole bunch of other designs have been ...