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 makes iron special?
Iron is the end of the road for fission and fusion, the lowest energy nucleus. It's also the strongest magnetic atom. Is this coincidence, or is there a deeper connection?
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Does matter-anti-matter burning happen in stars?
I asked ChatGPT at what temperature anti-matter can spontaneously be created and I was told that a billion kelvin would be enough, which puts it into the temperatures at the cores of stars.
That seems ...
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Why opacity enhancement of ICF fuel by high-$Z$ admixture is never considered?
The main mediator for the transport of heat from the hot burning region out into the cold region of the plasma is photons.
FACTORS THAT INCREASE GAIN On the one hand the addition of e.g. Pb ...
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Underlying Approximations Leading to the Vlasov Equation?
In classical gas theory, as taught in statistical mechanics classes, we learn that the statistical distribution function for each particle is described by the Boltzmann equation:
$$
\frac{\partial f}{\...
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Can a brown dwarf be ignited?
So, people love to talk about that time on the Manhattan Project where they were worried about setting off runaway fusion in Earth's atmosphere. Obviously (and luckily) that didn't happen, but I am ...
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Do neutron stars fuse elements?
I have read these questions:
In reality, they fuse the hydrogen nuclei (the cores of the atom) together into helium nuclei.
https://solarsystem.nasa.gov/genesismission/gm2/mission/pdf/NeutronStars....
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Fusion September 2024: Where are we with respect to "engineering break even"?
I'm a physicist, but fusion is not my field. I would appreciate any corrections on any misconceptions exposed in this question.
I understand that in a fusion reactor we supply energy to some sample of ...
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How does the energy released by fusion in the sun relate to the creation of pressure to stop the sun from collapsing?
When fusion occurs in the sun, it releases energy according to the mass loss due to fusing two nuclei into one. Apparently this keeps the sun from collapsing due to its gravitational force. However, I ...
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What is the purpose of toroidal magnetic field in tokamak fusion device?
From my understanding, pinching plasma to the center is the most important thing. And with Lorentz force, poloidal magnetic field from plasma current itself is pinching it to the center, this should ...
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How much energy per second would a nuclear reactor need to power a fighter jet?
Fighter jets typically require high amounts of thrust compared to other aircraft. Lets take the F-22 for example, and lets assume the F-22 powered by a nuclear reactor and the F-22 powered by a ...
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Hollow Conical Shell Z-pinch Lithium Penning Gas For $^6Li$ + $^2H$ => $^4He2$ Fusion?
It occurred to me that boiling $^6Li$ as the thermal step in a Z-pinch device, given lithium's low first-ionization energy, might be a better way of creating homogeneous ions for the subsequent ...
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Is there any formula for calculating the temperature required for nuclear fusion for a specific pressure?
From what I have gathered through my research I've come to the conclusion that the temperature required for nuclear fusion decreases with increasing pressure; this seems intuitive enough. However, I ...
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Can you create fusion through scattering?
Could you scatter deuteron molecules (D-D) at high energies into some heavy metal target such that at the time of impact the bond in the deuteron molecule is compressed to such a degree that fusion is ...
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Is cold fusion the only avenue for fusion reactors? [closed]
To my understanding, cold fusion proposes a solution to usable fusion reactions by finding a way to fuse nuclei at room or near-room temperatures. However, I also understand that improving energy in ...
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Can electrons or protons due to fusion reduce in their individual mass?
It's a ridiculous question, but that's why I am asking it after getting confused over a paragraph about nuclear fusion in my textbook.
The total mass of a stable nucleus is slightly less than the ...
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On the units of NRT-dpa electronic losses formula (Lindhard)
I'm trying to convert the PKA energy into damage energy following equation (5) of the NRT-dpa model article. In Fig. 1 you have an example of what you should get. Let's take $E=40keV$ (PKA), therefore ...
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Relationship between gravitational force and fusion energy in stars [duplicate]
From what I understand, stars like our Sun constantly have a gravitational force on their surface due to their mass, which is balanced out by the fusion reactions taking place in the core of the Sun.
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Finding the cross section for the proton-proton fusion reaction
I have been looking at the cross section $(\sigma)$ for the proton-proton collision in plasma.
From what I have researched, the cross section cannot be found experimentally so it must be found through ...
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Can Muon Catalyzed Fusion work in a Plasma?
From what I understand, muon catalyzed fusion works by injecting muons into the deuterium and tritium, which then they replace the electron shared between the hydrogen isotopes in a molecule, making ...
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Can X-rays compress plasma for fusion?
I know in ICF fusion, generally lasers are used to generate X-rays inside a holhraum to compress a duetirium tritium fuel pellet until it generates fusion reactions. I was wondering if the same ...
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Artificial Nucleosynthesis
Is it possible to artificially turn hydrogen into helium, let's say, and then go from helium to lithium and so on? I know that fusion reactors do that by fusing deuterium and tritium. Could this be a ...
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What is magnetic shear?
Can someone please summarise to me what exactly magnetic shear is? I know shear as $\tau=F/A$, and intuitively interpret is as, eg, a force on an object and the friction response being shear forces. ...
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Question about the use of the term 'mode' vs 'instability' in fusion experiments
I am currently trying to get to grips with MHD instabilities in fusion experiments, and I am confused at to why instabilities are sometimes referred to as modes? To my understanding, a 'mode' is a ...
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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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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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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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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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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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