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Questions tagged [fusion]

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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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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 ...
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Ok. I'll try again [closed]

A Hypothesis. In the Electromagnetic Donut variety of Fusion Reactors.. Using the EM Fields to bring the Plasma To but not pass the Fusion Threshold. A portion of the Plasma is brought passed it by ...
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1answer
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Gamma Photons vs. Muons; Which is more expensive [closed]

Which one takes more energy to produce? I ask as I theorize that keeping the plasma in a fusion reactor is very expensive. Muons, while useful, are too short lived. Maybe... Keeping the plasma at ...
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DT fusion at rocky flats [closed]

What are the occupational exposure concerns for DT fusion experiments? My friend was working with inertial fusion.
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1answer
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How do electrons rearrange themselves after a fusion reaction?

The hydrogen atoms can fused inside Sun core into helium without considering about the free electrons, however what about special* cases where two neutrally charged hydrogen atoms collide and fused ...
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1answer
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Forming a Neutron Star: inverse $\beta^-$ decay or electron capture?

There are three different kinds of beta decays: $\beta^-$: n $\rightarrow$ p + e$^-$ + $\overline{\nu}_{e^-}$ $\beta^+$: p $\rightarrow$ n + e$^+$ + $\nu_{e}$ electron capture: p + e$^-$ $\rightarrow$...
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Question about China's Artificial Sun

I have read recently in many websites dedicated to science that China has made an artificial sun hotter than the 'sun'. My question is how did they make a thing that can withstand such a high ...
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Lead catalyzed fusion

Consider the following setup: A beam of deuterons is accelerated towards a lead target. With sufficient acceleration (in the MeV range, nothing fancy...), I would expect some of the deuterons to fuse ...
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How could someone calculate the coulomb barrier transparency in 3 dimensions [duplicate]

Transparency is also called probability of transmission, or probability of quantum tunneling.
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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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How does Sun's fusion output compare to its gravity?

How does the total solar energy output compare to the total energy required to keep it contained (i.e. Sun's total gravity). In other words, is Sun's output "positive" if its gravity is factored in ...
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How do we contain nuclear fusion?

I understand that here on earth we create fusion at temperatures that are much hotter then our sun. What I want to know is how we contain those high temperatures safely. Also if any one can give an ...
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Does converting rest mass to energy instantly change the gravitational attraction it exerts?

Let there be two hydrogen atoms having 1.1 mass each. We use solar fusion to convert the two hydrogen plasma to helium with a mass of 2 and 0.2 gamma radiation. Before the fusion process gravity was ...
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4answers
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Fusion methodologies

Forgive my naivety but it seems to me all the attempts to create useful fusion concentrate on high temps or high pressures or both and samples of fusible material consisting of multiple nuclei. Is ...
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Biggest Fundamental Force Examples? [closed]

I know that this question sounds confusing but listen well, What I am asking which phenomenon that happens anywhere in the universe that best represents the four fundamental forces. Nuclear Fusion, ...
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1answer
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Using coil gun make two mass of lithium deuteride collide and start nuclear fusion

We already have hydrogen bomb, why controllable nuclear fusion so difficult? And why controllable necessary? If we can detonate a tiny hydrogen bomb, we can collect the energy, like laser nuclear ...
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Nuclear Fusion Proton-Proton Chain

When hydrogen nuclei are able to overcome the coulomb forces, two protons collide. As a result, one of them decays into a neutron and a positron and electron neutrino are emitted. However, isn't mass ...
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auto-refilled nuclear fusion generator [closed]

I read in a science article that in a nuclear fusion reactor, the energy we bring to the reaction is multiplied by a coefficient q. This coefficient needs to be at a certain level (around 7 if my ...
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How much would the lifetime of the sun change if the reactions inside ended at 3-Helium

This is assuming no other changes. I am aware the PPI branch makes up 87.1% of the reactions in the sun, and that the PP sequence as a whole powers the sun, but I am not able to tell the amount of ...
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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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1answer
28 views

Form of energy release

I know that fusion and fission can be esothermic processes if they happen between the "right" elements (meaning, indicatively, lighter/heavier than iron respectively). I always thought I got this ...
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2answers
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How is fusion reactor fuel initially accelerated?

If, in a nuclear fusion tokamak reactor, you start with neutral fuels, how do you accelerate the atoms fast enough to start the reactor? Or do all of the particles have to ionized to begin with?
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Fusion & vaporization of a solid

The values for electric dipoles in a salt (gas phase) are huge respect to organic molecules. The following seems a reasonable question (although it might be wrong): Is it possible to consider ...
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1answer
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Ideal MHD stability with a Fourier analyzed perturbation

I'm learning through the basics of ideal MHD instabilities and the textbook (Friedberg, Plasma Physics and Fusion Energy, 12.4-12.6) writes the linearized momentum equation in terms of the ...
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1answer
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What is a quasi-axisymmetric stellarator?

I know that a tokamak is a donut shape fusion confinement device with an axisymmetric magnetic field configuration. The stellarator is similar but its field configuration is non-axisymmetric. I've ...
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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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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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1answer
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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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1answer
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Are both ions and electrons assumed to be moving in plasma currents?

In a tokamak plasma, for example, an ohmic transformer is used to inductively drive current. In this scenario, is it simply assumed that the electrons are mobile and driving all the current in a ...
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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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2answers
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Does Nuclear Transmutation release or take in energy?

I wanted to know whether the bombarding a particle to transmute it into another particle releases or absorbs energy. For eg, I wanted to know specifically for O-17 formation: I found a question which ...
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Would it be possible to use lasers to plug the end holes in magnetic mirror confinment fusion schemes?

My first thought was that the plasma being not very dense likely wouldn't adsorb much of the light but I think you could set up symmetrical gain chambers so that any light going out one laser, and ...
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1answer
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When will hydrogen no longer be the most abundant nucleus?

In a recent question, we learned why hydrogen is currently the most abundant nucleon or element in the universe. Here I ask a follow-up: For how long will hydrogen be the most abundant nucleus? It ...
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Is there evidence of gas ever forming a black hole without being a star first?

Here's my general understanding of how gas particles form a black hole: 1) Gravity pushes gas particles together. 2) These fast particles create heat (from friction due to them rubbing together?). ...
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1answer
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Triple-alpha reaction rate

I'm trying to find a general equation for the fusion rate of the triple alpha process. I found this equation: The rate of energy generated by this process as a power law in $T$, centered around $10^...
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0answers
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Laser Powered Fusion Reactor

I've been doing research on Helium-3 fusion (2H + 3He -> 4He + 1p) and was thinking about how to overcome the Coulomb Barrier for this reaction, when an article from a science news website popped up ...
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How do fusion reactors deal with blackbody radiation?

The plasma of the ITER reactor is planned to be at 150 million K. Using the Stefan-Boltzmann law, setting the surface area as $1000\,\mathrm{m}^2$ (the plasma volume is $840\,\mathrm{m}^{3}$ so this ...
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1answer
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What does 'high-beta' mean for a fusion reactor?

I see the term 'high-beta' a lot, but cannot find a definition. When I type it into Google, I mostly see results about a Lockheed Martin fusion reactor project.....
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Are there processes other than fusion which can create very heavy elements? [closed]

Have there been hypothesized processes other than nuclear fusion which could possibly create heavy elements? For example these incredibly powerful particle accelerators we are continuously building ...
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1answer
51 views

How to generate plasma above 10^6 K without using neutral beam injection.

I want to make a model Tokamak fusion reactor to experiment with and toy around. I am willing to sink some money into its construction, but I cannot afford a neutral beam injector to heat the plasma. ...
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Magnetic confinement in a tokamak

I have a question about why exactly the twisting of the field lines in a Tokamak solves the magnetic confinement issue. My understanding is that the magnetic confinement issue arises in the toroidal ...
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3answers
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Why electron/ion beams are not prefered over lasers as driver for inertial confinement fusion?

Most of hi-end ICF research facilities, and proposals for future powerplant or space-ship propulsion use lasers as driver. Problems with lasers intense lasers needed (e.g. NdYAG 3rd harmonic ...
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1answer
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Minimum size of a “water star”

So I had this weird idea the other day. We know that stars form from simple matter (dust, gasses, etc) forming a gravity well, attracting to each other, until the amount of mass and density in the ...
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1answer
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Filling a flux surface in a tokamak or stellarator

Assume you have a magnetic confinement device like a tokamak or a stellarator. Let's assume further a configuration with closed magnetic field lines resulting in typical flux surfaces. If you now ...
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Energy from nuclear fusion? [closed]

Upon doing research on tge nuclear fusion reactors people build at home, Ive always heard that I will be using more energy than I make. So how could I change that and make energy off of the reactor?
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1answer
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Could we create an artificial sun? [closed]

based on dyson spheres.. imagine we construct an sphere of high radius R , then we fill the sphere with hydrogen, if the sphere is huge and the hydrogen is too then the gravity will make the ...
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1answer
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Is a dipole fusion reactor feasible?

It is well known that the earth's dipole-like magnetic field is able to confine charged particles to paths that spiral along the field lines. That's why we have auroras and the Van Allen radiation ...
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1answer
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Nuclear fusion difficulties

What is it that make nuclear fusion so difficult at low temperatures? There is plasma existing at low temperatures, so what does it make for fusion to be so difficult to reach at ambient temperatures?
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Can you combine protium and tritium to produce Helium-4?

Can you combine protium and tritium to produce Helium-4? I think they're a perfect match like a piece of puzzle since tritium just need another proton and electron to make a stable helium-4 atom. Also,...