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 theoretical efficiency of fusion?

What is the theoretical limit of the amount of energy that can be extracted from a fusion reaction? I am not talking about the practical efficiency of a reactor, but rather what fraction of the mass-...
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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
71 views

What is the shortest duration fusion reaction?

In a tokamak fusion reactor fusing hydrogen nuclei what is the shortest duration experiment that successfully fused nuclei. Is there a database with fusion reactions and their duration.
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309 views

Simulation of plasma in tokamak

I am reading some papers on numerical algorithms for simulation of plasma in the context of nuclear fusion in a tokamak. I am getting a little lost as there is a huge number of references, and it is ...
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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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Does a fusor emit dangerous radiation?

I noticed some online videos where people have built these things in their house or garage. Is it dangerous to do so? The high voltage appears to be a potential hazard, but what about radiation -- ...
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247 views

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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255 views

Nuclear fusion ignited by neutron capture

Does anybody know if there was some attempt to make a hydrogen (fusion) bomb using neutrons released from the fission primary? e.g. using $^{10}\text{B}$ hydrate as a fuel? Assuming reaction $$^{10}\...
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1answer
78 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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48 views

Nuclear Fusion and Quantum Annealing

This is a pie in the sky idea, and a problem finding sort of question that can probably be dismantled easily, but in light of alternative energy needs with climate change, I think it would be ...
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30 views

Is there a mathematical model for predicting when gamma rays are produced in radioactive decay?

My understanding of gamma ray emission from radioactivity is that the daughter particle is in an excited state, which then produces a gamma ray as the electron drops energy levels. In the case of ...
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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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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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Why the nuclear fusion 6Li+D and 7Li+P reactions happens 10 time less than H+11B?

The first two reactions generates 2 alphas and the boron one generates 3, but boron has 2 more protons than lithium so should repels more to hydrogen. I suppose is a question of nuclear states, but ...
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Does a high-velocity ion being neutralized by an electron emit Brehmsstrahlung radiation?

I'm curious about a point of the physics of Polywell electrostatic confinement fusion devices. One of the key claims made in the design is that by confining some "low temperature" electrons to a ...
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127 views

What determines direction of plasma current in tokamaks?

Plasma current is used to ohmically heat fusion plasmas and provide stabilization of grad-B drift in tokamaks as the resulting poloidal motion of the charged particles results in the particles ...
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54 views

Ion acoustic waves in a deuterium plasma?

Has anyone ever experimented with inducing ion acoustic waves in a deuterium plasma? Perhaps to observe the phenomenon of Landau damping? Or to heat the plasma for fusion reactions to occur? And, ...
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1answer
49 views

Can stellar nucleosynthesis processes other than deuterium-lithium, i.e., oxygen-burning, take place in a reactor?

It is known that gravitational confinement and supernovae facilitate the synthesis of heavy nuclides; and, that magnetic confinement is thought to facilitate the deuterium-lithium fusion in human-...
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Logic behind Coulomb explosion fusion?

Many experiments seem to have been done where the experimental setup consists of an extremely short, but intense laser pulse, impinging on e.g. deuterated plastic of some sort or some "jet" of nano ...
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Can air plasma ions in a fusor fuse?

I know that hydrogen ions will fuse in a fusor but what about air ions? Can air plasma ions in a fusor fuse? https://en.wikipedia.org/wiki/Fusor, if so, under what cicumstances, and how would I ...
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2k views

In the middle of depletion layer of reverse biased p-n junction is the electric field almost zero?

My textbook states: Due to reverse biasing the width of the depletion region increases and current flowing through the diode is almost zero. In this case electric field is almost zero at the ...
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96 views

Flyback transformer for fusor?

I've always wanted to construct a farnsworth nuclear fusor. I recently ordered a 3-6 volt to 400,000 volt flyback transformer, and was wondering if that could be used in a fusor setup
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71 views

Would a charged particle moving through a carbon nanotube experience no or negligible bremsstrahlung?

The context here is for beam-target fusion. The supposition is that it would actually possible to achieve breakeven with an accelerator-based system and cold targets based solely on a modest ...
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Understanding the concept of cross section

The cross section is a tiny area, measured in barns ($10^{-28} \mathrm{m^2}$), which relates to the probability of a reaction. But I have trouble interpreting that number. For example how can I ...
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Can a Magnetic Confinement Fusion Tokamak generate An Axial Vertical Field?

A question from a complete novice: Perfectly aware that tokamaks confine plasma in a toroid, could they potentially generate an axial vertical electro-magnetic field as a side-effect, or is it ...
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Using a Neutron Poison In $D$-$T$ Fusion Reactors to Capture Neutrons

One of the major problems of the $D$-$T$ fusion reaction is that it releases a 14MEV neutron. In large numbers, these neutrons irradiate the chamber walls and wreak havoc on the metallic lattice, ...
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How useful could neutrons as energy directors in fusion (similar to laser-accelerated electrons)

If you directed fast,'hot' neutrons towards a small amount of homogeneously mixed fusion fuel at a point, is fusion likely where the involvement of the neutrons need only be in providing energy and ...
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What can be learned from Wendelstein 7-x experiment?

This experiment achieved a stable plasma for 26 seconds. What do we learn from it in general(why it was done)? and specifically about the possibility of achieving positive energy flow ($Q>1 $) by ...
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'Forces' enacted by hot neutrons in fusion bomb - Pauli exclusion

Are Pauli exclusion 'forces' on a neutron 100% electromagnetic (Lennard-Jones seems more acute relationship compared to electrostatic force) If so does that neutrons have two forces between them - '...
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1answer
27 views

Can another element “burn” at the same rate as hydrogen does in our sun?

From what I understand our sun doesn't actually "burn", instead a nuclear reaction is taking place, which is the cause of heat, light and a electromagnetic radiation. I believe this is called Hydrogen ...
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40 views

Why is this reaction considered a nuclear fusion when the daughter isotope has a nucleus with the same mass?

I understand that in nuclear fusion, the colliding particle unites with the parent and fuses into a single nucleus with a higher mass. Sometimes other small particles (n, p) are given off. However, ...
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Calculation of number of nuclear fusion reaction per cubic meter or kilo

In wikipedia article about Nuclear fusion there is a list of nuclear fusion reaction here. Is there a equation how to calculate number of nuclear fusion reaction per second per cubic meter or per kg ...
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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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35 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
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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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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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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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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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56 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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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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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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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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What is the probability of fusion reaction happening with energy less than the coulomb barrier (probability of reacting nuclei quantum tunneling)?

$ E_{out} = 4 \pi n_1 n_2 (m_0-m_a) c^2{(\frac {m}{2k_B T})}^{3/2} \int_0^ \infty \sigma(v) v^2 e^{\frac {-mv^2}{2k_B T}} dv$ $m_0$ is the sum masses of the reacting nuclei, $m_a$ is the sum masses ...
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CNO fusion using particle accelerator?

The CNO cycle is a catalytic fusion reaction that produces energy in stars larger than the sun. It converts four protons into a helium-4 nucleus using a cycle of carbon, nitrogen and oxygen isotopes ...
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What changes does Lockheed's fusion concept have which makes it better than magnetic mirrors?

Magnetic mirrors were thought to be a viable solution for fusion power. But then, we found out that most of the plasma would simply escape. Is this right? So, then we realized that this method might ...
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132 views

what is the nuclear cross section dependent on?

I understand that the nuclear cross section determines the probability of fusion taking place. When I was talking to my friend he said that the cross section doesn't depend on anything but the ...
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Why is the nuclear cross section for fusion so small?

Recently, I have learn't about the Gamows factor, and I have plotted it. Then I realized that the probability of Deuterium and tritium fusing at a temperature of 150 million kelvin when they collide, ...
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Why should we equate the formula for translational kinetic energy of monoatomic molecule with $P$ to find $T$?

In the nuclear fusion reaction, $$ H_1^2 + H_1^3 \rightarrow He_2^4 + n_0^1$$ suppose I have been given the repulsive potential energy (say $P$) between the two nuclei. I need to find the ...
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83 views

Fusion inside a planet with high concentration of radioactive elements?

If an Earth-sized or larger planet had sufficiently large amounts of radium, thorium or uranium, couldn't the resulting fission trigger periodic fusion of hydrogen? I'm thinking of fission happening ...
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How much of fusion energy is positron-electron annihilation?

Stellar fusion involves protons becoming neutrons, which means ejecting a positron. Positrons annihilate electrons. This must deliver some energy in stellar fusion. But how much of the energy from ...