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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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}...
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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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93 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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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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1answer
53 views

How hot should the plasma be for nuclear fusion?

Regularly we can read success stories like "physicists obtained a 100 million Celsius plasma and held it for 102 seconds". (These are recent data from the EAST tokamak.) But what are their ...
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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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43 views

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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Theorical efficiency of Chirped Pulse Amplification HB11 fusion reaction

I read that scientists finally reproduced a more efficient fusion with a novel approach. They accelerate hydrogen inside a pellet with a LASER. A single H atom produces three $\text{He-4}^+$ nuclei. ...
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119 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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405 views

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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258 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
86 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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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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20 views

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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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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39 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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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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48 views

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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202 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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1answer
64 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
51 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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47 views

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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72 views

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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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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111 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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72 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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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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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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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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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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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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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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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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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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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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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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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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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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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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Electrostatic Plasma Confinement Fusor

I wish to build a Fusor. Now, in order to build it, a high voltage is required generally achieved through Neon Sign Transformers. If I want to achieve voltages 25 kV or more, how am I supposed to do ...
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Could one, with enough electricity to spare, use particle accelerators to mass produce heavy elements

If electrical, and economic limitations are ignored, would it be possible for a civilization to mass produce many millions of tonnes of useful heavy elements using particle accelerators? Could they ...
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Why is the $\rm CNO$ cycle is much more efficient than the $p$-$p$ cycle?

Why is the $\rm CNO$ cycle is much more efficient than the $p$-$p$ cycle?
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1answer
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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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'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
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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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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, ...