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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Does the definition of "energy produced" by the LLNL's NIF fusion experiment include the energy delivered?
A figure in a 23 Nov 2023 article on Optics.org shows that more energy was produced than delivered. That is, the area or the red region seems to represent the energy produced.
But a similar figure in ...
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Muonic Hydrogen Dissociation
Is the dissociation energy of a muonic molecular hydrogen ion the same as an ordinary molecular hydrogen ion? Would the cross-section for dissociation be the same as an ordinary molecular hydrogen ion?...
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Fusion in the sun for 4 hydrogen to Helium-4. How is the energy produced
So please correct me if I am wrong but:
First 2 proton’s (each with an electron) fuse together,
The mass stays the same so no energy is produced?
Then 1 of the protons turns into a neutron with a ...
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Why does a Tokomak work on low pressure? In most other places high pressure seems to be required for fusion
In a star gravity creates the pressure, and fusion reactions create the temperature for fusion.
In a thermonuclear bomb the fissile shell around the core exploding inwards create the temperature and ...
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What mass fraction of a main sequence star produces energy?
Only some fraction of the total mass of a main sequence star produces energy in the star's centre through the pp-chains, or in heavy stars, the CNO-cycle. My question is about the mass fraction where ...
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Muon-catalyzed fusion: muon number
I recently read a paper "Meson-catalyzed fusion in ultradense plasmas" (it is behind a paywall: only subscribers to Physical Reviews E can read it) that claims that muon-catalyzed fusion in ...
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Efficient way to convert hydrogen atoms to neutrons?
Can a hydrogen atom be converted to a neutron with a sufficiently high energy photon? Or perhaps via a pair of photons having total energy of about 800 keV? One photon would have an energy of say ...
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High-energy neutron multiplier
Are there any materials that can function as efficient high-energy neutron multipliers? I have read about the utilization of Beryllium and Lead as neutron multipliers, but they seem to only be ...
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Green's function for a Hirsch-Farnsworth fusor
I'm writing a proposal for building a Hirsch-Farnsworth fusor at my university using a vacuum chamber, deuterium, and high voltage power. A loop of wire inside the chamber is set at a negative voltage ...
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Ideal ignition temperature for a D-T plasma fusion reaction
I've been trying to calculate the ideal ignition temperature for a 50-50% Deuterium-Tritium (D-T) reaction. In the literature this value is $4.4$keV and I'm getting $5.2$keV. Here's how I'm carrying ...
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Are there spectra that "prove" that measured energy excesses came purely from deuterium-tritium fusion reactions at the NIF during ignition events?
More energy was produced than was supplied by ultraviolet (UV) lasers (creating x-rays in the gold chamber wall to compress the spherical hollow capsule creating a dense, high-temperature, high-...
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HB11 fusion Engine
Looking for a way to achieve torch ship performance (https://www.projectrho.com/public_html/rocket/torchships.php#torchdrive)
Without strapping my reactor/engine to the outside of my ship. The main ...
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During fusion, how does mass turn into energy?
This is my (flawed) understanding of how fusion basically works:
Let's assume that a fusion reaction has a net gain in energy.
First, there is an input amount of kinetic energy to get the two light ...
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Power from CNO Cycle Fusion
There are all sorts of projects trying to get power from fusion reactions.
The best known and funded are the Tokamaks, big expensive crush Deuterium and Tritium (He3 sometimes) plasmas and spew ...
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How is volume defined and measured in nuclear physics, in particular regarding the Sun’s core? [closed]
The Sun’s core is, from the micro/quantum perspective (from what I've read) the constantly moving phenomena of nuclear fusion (as the Earth is mostly the constantly moving phenomena of stable atoms ...
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In a tokamak, is there a density-dependent limit on plasma current?
In a tokamak, the kink limit places an upper bound on the magnitude of the plasma current. For example, Parisi and Ball (2019) write this limit as (p. 246)
$$I\lesssim\frac{1}{q}\frac{2\pi}{\mu_0}\...
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Could lithium deuteride sustain a "cold" chain reaction?
When Lithium 6 absorbs a neutron (thermal or not) it reacts forming an alpha particle and a tritium. The formed tritium has an average kinetic energy of 2.5 MeV. That kinetic energy is way higher than ...
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Why lasers are used in inertial nuclear fusion?
Why in inertial fusion are used laser rays but not, for example, merely focused light? Is there a problem with precision of focusing or power density?
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Confusion about energy conservation for fusion and fission (binding energy and $Q$-value)
In a nuclear reaction, a system consisting of a nucleus or nuclei lose mass, and this mass gets turned into energy, which is quantified by $E=mc^{2}$. But I'm conceptually confused. According to ...
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Improved estimate of density of free neutrons in solar core
In an answer to this question:
Free neutrons in the sun's core?
I made a very rough attempt to estimate the density of free neutrons in the solar core. There is some non-zero rate for production ...
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Why does the Nuclear fusion rate decrease with temperature after a point?
According to here the Fusion rate for D-T peaks at a little under 1E9 Kelvin and decreases afterwards. Why is this? Why does the rate stop increasing?
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How do protons fuse in the sun?
I know that Nucelar fusion in the sun requires quantum tunneling to occur, as otherwise the Sun's core wouldn't be hot enough to overcome the Fusion barrier.
However while the 2nd and further stage of ...
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What’s the lightest you could make a "star" if you made it out of different materials?
What’s the lightest you could make a "star" if you made it out of different materials?
How large would the "star" be?
For example according to here https://astronomy.stackexchange....
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Randomly think about how the world will end because I have homework to do. Please help me think this through [closed]
First off, I just want to say that i do not hold any degree of any kind, except a forklift certification but I do love space and I think about it to the point where I believe. As I am sitting in front ...
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Determing for particle density of many particle species in plasma
For quasi-neutrality plasma of many species, the relation of electron density and ion density said that
\begin{equation}
n_{\text{e}} = \sum_{s}Z_{\text{i},s}n_{\text{i},s},
\end{equation}
where $n_{\...
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What’s the minimum mass required for a star to burn helium?
What’s the minimum mass required for a star to burn helium? I’ve liked online but I’ve gotten inconsistent answers.
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What are some practical problems with static electrical confinement of plasma?
Plasma and fusion physics experts, help me with this one: Suppose we have a D-T plasma with net positive electrical charge inside a positively charged metal sphere. As the containment sphere's net ...
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How Should the True Energy Gain of the NIF's "Scientific Breakeven" Fusion Experiment be Calculated?
According to this article "LLNL’s experiment surpassed the fusion threshold by delivering 2.05 megajoules (MJ) of energy to the target, resulting in 3.15 MJ of fusion energy output." It isn'...
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Theoretical calculation for deuterium tritium fusion
How would a deuterium-tritium fusion feynmann diagram look like in terms of QHD (i.e meson exchange like eta,pi,sigma,omega,...)? I couldn't find anything online whilst this would be quite an ...
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Why it is not possible to reach the sun if we are able to create plasma? [closed]
if we are able to create plasma in isolated environment possessing temperature much more than temperature of sun then why are we not able to create something that can go to the sun?
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How does an electron absorb the energy released during inelastic collision between a neutron and the nucleus of a hydrogen atom?
In atomic collisions,does the neutron fuse with the proton of hydrogen and release a photon which is absorbed by the electron which then gets excited to higher energy state?
Or do the neutron and ...
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Is there an intuitive picture for quasi-isodynamic versus quasi-axisymmetric versus quasi-helically symmetric flow in stellarators?
I recently read a paper in which Alan Boozer says,
The W7-X stellarator was made quasi-isodynamic rather than
quasi-symmetric in order to minimize the parallel currents as well as
the ripple-trapped ...
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Are there any research mentioning the principle of tornados or maelstroms in plasma physics related to fusion?
There are many different ideas and concepts related to design of fusion reactors and handling plasma confinement, but what about designing one around the principles of a maelstrom or a tornado? Is ...
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Nuclear fusion by Z-pinch without Marx generator?
The Marx generator was invented by Erwin Marx in 1924 (1). This electric generator is an assembly of capacitors and spark-gaps. The capacitors charged in parallel and are discharged in serie. This ...
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How does the second stage of a fusion bomb create and maintain the needed pressure?
My understanding of the second stage of a thermonuclear bomb is as follows:
X-rays from the first stage compress the "tamper", thereby igniting the fission sparkplug, and that the resulting ...
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Why do most MRI machines and fusion reactors use helium-cooled superconducting magnets instead of cheaper, higher-temperature nitrogen-cooled ones?
I am always hearing about the high (and increasing) costs of helium, as well as the difficulty of handling it....
Are there no high(ish) temperature superconductors that can create a strong enough ...
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Why are nuclear fusion reactors difficult?
The first fission bomb was created in 1944, and the first fission reactor in 1951 (and actually productive one in 1954). This delay seems possible to explain by there being a larger amount of initial ...
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What "changes" in the quantum state of bound nucleons that cause that system to have mass defect?
The electric field in an excited hydrogen atom is non-zero over a bigger volume than the electric field in a ground-state hydrogen atom. The energy associated with this extra electric field must be ...
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Derivation of pressure balance equation for a toroidal geometry [closed]
Derivation of pressure balance equation in toroidal geometry
$$
\boxed{
\frac{\mathrm{d}p}{\mathrm{d}r} + \frac{\mathrm{d}}{\mathrm{d}r} \left( \frac{B_{\phi}^2}{2\mu_0} \right) + \frac{B_{\theta}}{\...
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Exchange interaction and nuclear fusion
Most texts about nuclear fusion say that the reason it is so hard to get protons to fuse is the strong Coulombic repulsion between them. However, it seems to me that at close distances, protons should ...
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Why does deuterium fusing with a proton produce a gamma ray?
For the pp chain, the second process is listed as the d(p,γ) 3He reaction: D + p --> 3He + gamma ray.
I cannot find an explanation why a gamma ray is created in this process. Can anyone explain why ...
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Would an intersecting plasma in a fusion reactor increase yield due to the collision of particles in the plasma?
It seems to me that having a plasma “stream” in a tokamak that intersected itself would increase the number of collisions happening between particles. Is this feasible or is it negligible in the face ...
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How is the branching ratio defined for nuclear reactions?
The Wikipedia page for candidate nuclear reactions for terrestrial fusion power notes that the D + D and He-3 + T reactions can proceed through either of two alternative routes; for example:
(2i) D ...
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Is the universe getting hotter? Brighter?
Due to their fusion processes every star is radiating massive amounts of photons and (to a lesser extent) neutrinos. Are all of these getting absorbed in matter over time, warming it, or is the total ...
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What would the nucleus of a water planet be like?
If we have a planet made out of water, would it be all solid? What about the nucleus? Would it depend on the size of the planet?
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Is the energy of matter (via $E=mc^2$) actually available to do work?
If energy is functionally defined as the capacity to do work, then in what sense does mass offer a lot of energy (via $E=mc^2$). Most people responses I've seen to similar questions state “there’s a ...
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It is possible to combine two heavy elements into one?
Is it possible to combine say two uranium atoms into very heavy new element? Periodic table ends around 115 today, but can it go forever technically?
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How can the binding energy per nucleon graph be useful if you can't compare "all" products with "all" reactants?
How can the binding energy per nucleon (BEN) graph be useful if one can't compare "all" products with "all" reactants?
Take the fission process of Uranium to Thorium:
$${}^{238}U \...
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What does thermal (non-)equilbirum mean in the context of a fusion reactor (such as the Helion reactor)?
A while ago, there was a question here asking about the impact of Todd Rider's thesis about various fundamental limitations to fusion reactor efficiecy. That question was mainly concerned with why ...
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Mass per nucleon graph
I am a high school student and am struggling with understanding the significance of the mass per nucleon graph.
What does this graph show with regard to nuclear reactions? (y-axis: M/A, x-axis:A) I ...
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