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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13 views

Where does the negative electrode come from in an HB11 fusion reactor?

I'm an electrical engineer. Throughout my education, I was taught that current always has a return path. This understanding applies to everything. Batteries use an electrolyte to strip electrons ...
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Why doesn't the nuclear fusion in a star make it explode?

I have a rather naive question. In stars such as the Sun, what prevents the whole thing exploding at once? Why is the nuclear fusion happening slowly? I can only assume that something about the fusion ...
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Looking for a more complete explanation of muon catalyzed fusion [closed]

I've read quite a few explanations for muon-catalyzed fusion. I'm laying down my understanding below with clear questions -- some may be fundamental so please don't shoot from the hip, I would be very ...
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In fusion inside stars (sun) or very hot gasses, how do the electrons get bound and what about tritons and D-T vs D-D fusion?

Most texts I've read focus on just the nuclei to begin with, but eventually start talking about Helium (or other) atoms and isotopes. A few aspects aren't clear to me and I'd be grateful for some ...
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Does the proportion of strong nuclear force in a star change during nuclear fusion?

I read that the SNF accounts for 99.9% of the mass of an atom. So if 4 hydrogen atoms become 1 helium atom during nuclear fusion does that change the proportion of SNF as we have 4 SNFs becoming 1 ...
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Why do stars get bigger and brighter when older?

As stars age, the concentration of Hydrogen in the core decreases which lowers the power output, causing an imbalance between outward radiation pressure and inward gravitational pressure. This causes ...
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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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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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As neutrons are more massive than protons, does the Sun increase its mass while fusioning elements?

Where is the mass coming from when neutrons are produced from protons in the Sun? If a positron is made, will it possibly annihilate with an nearby electron?
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Can a Magnetic Confinement Fusion Tokamak generate An Axial Vertical Field? [closed]

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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Why is the weak force the main limiting factor when it comes to the $p$-$p$ fusion chain, instead of the quantum tunnelling effect?

For the $p$-$p$ fusion reaction chain occurring in the sun, why is it that the main limiting factor placed on the time scale of the initial proton proton fusion into helium due to the fact it is a ...
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88 views

Why is humanity investing so little on fusion research? [closed]

Optimists expect fusion industry to be a reality in 2080 to 2100. Fusion means clean and unlimited amount of energy, it is the fuel of the universe. Fusion will solve most of our time problems ...
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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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1answer
52 views

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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Can the fusion of deuteron-like nuclei form a new type of periodic table

In late 2019, The Indian Lattice Gauge Theory Initiative, theorized the existence of exotic particles, "which can be formed through the fusion of heavy baryons, similar to the formation of nuclei of ...
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How do we know fusion energies?

Crucial to our understanding of stellar evolution is the energies involved in nuclear fusion reactions. How do we know those energies? How do we know which fusion reactions take place, at which ...
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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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Do the MHD equations break down under certain circumstances (and possible connection to fusion experiments)?

The Euler equations produce singularities (in finite time) under certain conditions see here.  When rings of fluid approach each other,  in certain simplified scenarios,  the Euler equations that ...
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Can artificial fusion have the same power density as in Sun's core?

I recently read about solar core, and found that the power density is only 276.5 watts per cubic meter. This seems rather low to me, but on the other hand the Sun is an enormous object, so the total ...
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1answer
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Evolution of red dwarf stars

While low mass stars (initial mass approximately $0.1 M_\odot$ to $0.8 M_\odot$) are quite numerous, their evolution seems to draw relatively little attention. The lower central density and ...
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Why do later fusion stages in a star last shorter?

When most of the hydrogen in the core of a massive star has fused to form helium, the next fusion stages (helium, carbon, neon, oxygen, ...) produce less and less energy in a single fusion reaction. ...
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What is the force at play in the emission of neutron out of Helium-5

On nuclear fusion, Wikipedia reads (about Tritium-Deuterium fusion): The (intermediate) result of the fusion is an unstable 5He nucleus, which immediately ejects a neutron with 14.1 MeV. The recoil ...
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What is the largest obstacle in practical helium-3 fusion? [closed]

I've been busy looking into clean, sustainable energy solutions (for a project) I ran into He-He fusion of the isotope He-3, and most of it looks more beneficial than the traditional D-T fusion due ...
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Heavy elements creation [duplicate]

Would elements heavier than iron not be extremely rare if only created by supernovae? I believe all elements above hydrogen are created in the star's corona. Hydrogen fusion is not possible in star's ...
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Spherical Electromagnet Formed By Six Coils For Plasma Containment and Nuclear Fusion [closed]

Several years ago I have proposed an open source spherical magnetic vessel to contain plasma for nuclear fusion which can be seen by following this link. A photo of it is seen below. A question here ...
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How does binding energy work?

I do not have a very advanced understanding of binding energy and atomic mass but in my classes, I have learned that the atomic mass is equal to the sum of the number of protons and the number of ...
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Hydrogen bomb without fission stage

The majority of existing nuclear warheads are Thermonuclear devices implementing the Teller--Ulam design. It includes a first stage of "traditional" nuclear fission explosive (Uranium and/or Plutonium)...
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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 this arrangement of thingys in this light-induced fusion reactor?

Here is a photo from inside a light-induced fusion reactor at the National Ignition Facility, California. Image source: Wikipedia I'm not sure what those thingys all around it are but I assume they ...
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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, ...
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Fusion in Sun's core [duplicate]

I was reading nuclear physics in which it was mentioned that the coulomb barrier for proton is 400keV corresponding to a temperature of 3 billion Kelvin.I want to know then how does nuclear fusion ...
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How does the Sun provide enough energy to fuse protons?

Given that the sun’s temperature is lower than the temperature needed to fuse two protons. How does the sun provide enough energy for this fusion to happen? Has it do something with tunneling and $E =...
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Is first light fusion solution possible to work?

This company is running a project with extremely high pressure and low temperature https://firstlightfusion.com/technology/#our-approach Their idea is roughly by using a railgun, accelerate a ...
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Does fusion only occur with ions?

In nuclear fusion, the particles require enough energy to overcome the Coulomb barrier. The Coulomb barrier is caused by the Coulomb force, which is created by the protons repelling each other because ...
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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 would I go about calculating the energy input needed for a cyclotron reactor?

I'm trying to do some math regarding cyclotron reactors. I've figured out how to calculate the radius of a particle's motion in the cyclotron, a rough way to calculate energy output, but I have looked ...
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Is a chain fusion reaction of deuterium oxide (heavy water).possible?

I think it is the case that at very high temperatures that two deuterium atoms can be made to fuse to produce helium and a release of energy. I think under appropriate physical conditions this can ...
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How are thermonuclear weapons possible?

Given the fact that thermonuclear devices are a mix of fission through enriched uranium whose energy initiates the fusion in surrounding deuterium. Question is (how come) fission raises temperature so ...
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Energy from fusion beyond iron peak

In the diagram of nuclear binding energy per nucleon Eb/A (vertical axis) and mass number A (horizontal axis), Fe-56 has one of the highest values. Many authors state that nuclear fusion can only ...
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Is gravity a factor for sustaining fusion?

Does gravity affect a Fusion reactors ability to sustain a reaction? If so has there been any experiments done or planed for in space? Holding / maintaining shape might be a lot easier with less ...
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Any way to definitively determine the products of deuterium-deuterium fusion?

I was doing some reading and came across these two reactions: $D + D \rightarrow \:^3He + n + 3.27 MeV$ and: $D + D \rightarrow \:^3H + H + 4.03 MeV$ (from here: http://hyperphysics.phy-astr.gsu....
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How is the energy output released in a proton-proton fusion reaction?

$$\rm p + p \to {}^2H + e^+ + v_e$$ The net energy output for this reaction, not including the electron-positron annihilation that likely would occur, is 0.423 MeV - according to my math and sources ...
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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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Could you use the detonation of a Hydrogen bomb or atomic bomb to start a nuclear fusion reactor [closed]

Would this lead to a reactor that produced more energy than you put in?
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Is high temperature **required** for nuclear fusion?

Tl;dr: Can fusion be achieved only by speeding up particles to high enough speeds to smash into each other? I know that it is necessary for protons, or any oppositely-charged particles for that ...
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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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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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