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1answer
17 views

So how much fuel does a hypothetical fusion plant need?

Reading about potential fusion plants it's easy to get the impression that we have nearly infinite access to the fuels required. But looking aside form how much we have available, I am interested in ...
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0answers
15 views

Speed of fusion reactions compared to fission reactions?

How do the reaction rates of fusion and fission reactions compare? Is one faster than the other? What effect does this have on nuclear weapon designs?
6
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1answer
110 views

Why is a stellarator-type nuclear fusion reactor so oddly-shaped?

My first impression: It's a mess. Why is it shaped like that? I can't find any info about its shape other than it's a special arrangement of magnetic coils. (link) Here's some more images of it on ...
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1answer
77 views

Why did they start Wendelstein 7-X With Helium?

Just saw the first Hydrogen plasma at the Wendelstein reactor. I haven't found anywhere that gives a good explanation as to why they first used a Helium plasma - can anyone shed any light?
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2answers
76 views

How much iron would result of fusing a human body?

While discussing nonsense plots, a friend and I ran into the question of what would happen to a human enclosed perfectly with an enormous amount of energy, Antimatter or fusion level energy. It was a ...
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0answers
23 views

How is the interaction radius of fusion reactants determined?

To calculate the Coulomb barrier between two fusion reactants, the interaction radius (also called the fusion radius), r, must be known. How do I find the interaction radii of different nuclei?
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0answers
54 views

Is it possible for oxygen in the ocean to undergo nuclear fusion?

Could the oxygen in the ocean undergo oxygen burning (uncontrolled self-sustained fusion) if struck by a very large meteor or exposed to a similarly devastating cosmic catastrophe? Is it possible for ...
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2answers
102 views

Temperature of fusion in the Sun vs. fusion in controlled experiments on Earth

I recently learned that hydrogen fusion (i.e., hydrogen to helium) experiments on Earth have been successful at temperatures in excess of 100,000,000 degrees Celsius. However, I also learned that ...
2
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1answer
54 views

Is neutron-neutron fusion viable?

Do I get unusual baryon maybe like pentaquark or just a pair of conjoined twin that is very unstable?
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2answers
121 views

Why do people say nuclear fusion is 50 years away? [closed]

This '50 years' number is floating around media pretty consistently, even the ITER road map claims that the first commercial reactor will happen post-2050. But why is that? I understand that there is ...
1
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1answer
183 views

Could atmospheric muons be used to catalyze nuclear fusion?

https://en.wikipedia.org/wiki/Muon-catalyzed_fusion I read above that some work as been done investigating whether muons could be used to catalyze fusion of deuterium and tritium. Apparently they can ...
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0answers
52 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 ...
2
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0answers
39 views

Could anyone explain to me how the products of nuclear fusion/fission are predicted? [duplicate]

I have an idea of how quantum mechanics work, but I know too little to understand which products are a result of certain reactions like bombarding a certain atom with neutrons or just by natural ...
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0answers
48 views

Can a spheromak propagate in vacuum?

I recently learned about (and am now fascinated by) spheromaks. I am no expert on plasma physics, but as I understand they are analogous to propagating toroidal vortices (smoke rings), but with plasma ...
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0answers
28 views

Why can't electrostatically accelerated deuterium beams neutralized by electrons produce net energy fusion? [duplicate]

I was looking through the various nuclear fusion approaches and it struck me that they all suffered from one of two problems. Either they wasted a lot of energy trying to accelerate fusion fuel to the ...
2
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2answers
61 views

Why does the core of a low mass star contract after reaching electron degeneracy?

I am learning about the lives and deaths of stars with a solar mass of 0.4-2. What I understand is that once the star stops hydrogen fusion after using up all its hydrogen, the star leaves the main ...
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1answer
798 views

Reason why stars do not produce elements heavier than iron

In his book "Origins", Neil deGrasse Tyson says that "if you seek to split iron nuclei apart, you must them with additional energy. On the other hand, if you combine iron atoms they will also absorb ...
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1answer
52 views

Fusing Hydrogen with lightning

I've been reading about fusion recently (Specifically Deuterium fusion) and a friend of mine asked me if it was possible to fuse two Deuterium atoms with a lightning strike? Now this question has a ...
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0answers
70 views

How can we produce gasoline with nuclear fusion and without fossil fuels? [closed]

If all fossil fuels were suddenly to run out tomorrow, but we also were to discover an easy way to produce energy from nuclear fusion, how might we produce gasoline? Could we do it in a way that is ...
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2answers
120 views

In a nuclear reaction, where does the energy go?

Lets say two hydrogen fuse together, where does the energy released go? Is it carried away as momentum imparted on the helium atom? Is it carried away in neutrinos? Is it carried away as gamma rays? ...
-1
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1answer
113 views

Mass loss for Fusion energy? [closed]

I am thinking how you can estimate the mass loss of the fusion energy for 1 kWh. I think you cannot use Einstein's $E=mc^2$ to calculate the mass loss in the fusion reaction of the Sun. How can ...
-1
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1answer
62 views

In what ways does the sun output energy?

I'm curious about the energy output of the sun, and how it breaks down. What fraction is from EM radiation, solar wind, neutrinos, et cetera? How does energy output vary over the EM spectrum? I was ...
25
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1answer
2k views

Using nuclear devices to terraform Mars: Elon Musk's nuclear proposal? [closed]

Elon Musk has recently suggested Using nuclear devices to terraform Mars. In the past, comet related ideas were mooted, but Musk seems, to me anyway, to be a man in a hurry and perhaps his idea has ...
1
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1answer
64 views

How does fusion work in the Sun if neutrons have more mass than protons?

According to my textbook, the next result of the fusion reactions in the Sun is: 4H -> He + neutrinos + gamma photons However, if hydrogen atoms are basically a proton and helium atoms are 2 protons ...
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2answers
135 views

How can the magnetic field of a tokamak or stellatron hold against the outwards plasma pressure?

I understand that magnetic containment structures like tokamaks generate a toroidal magnetic field in which the plasma particles move in helices around the field lines, because of the Lorentz force. A ...
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2answers
38 views

Are known (“old”) elements being made synthetically using fusion?

Are known ("old") elements being made synthetically using fusion? I hear about research about making new heavy elements, but type "making known elements" on Google and nothing comes up. Are any known ...
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0answers
57 views

What happens to Hydrogen-Boron plasma at 3 billion Kelvin?

A recent popular report states (beware, I believe it is not peer reviewed and this slightly smells like a PR stunt) that a private company TriAlpha has made some notable progress towards ...
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2answers
95 views

What causes the death of the Sun?

In a previous question I learned that in each second only a miniscule portion of the total hydrogen in the Sun is converted to helium and that the number is 1/10^18 of its mass converted each second. ...
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1answer
121 views

Where is the Hydrogen the Sun consumes?

I understand the Sun consumes 600,000,000 tons of Hydrogen each second. Where is this Hydrogen? Is all the Hydrogen the Sun will ever consume inside it or are there vast amounts of Hydrogen in space ...
0
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0answers
14 views

Measured versus Predicted Energy gain in Tokamaks with size

Does there exist a known relationship between the energy gain of Tokamaks in dependence of their size? How do fusion engineers can predict how much gain will a given Tokamak size deliver? Do they just ...
0
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0answers
102 views

Neutron energy inside reaction of proton-boron fusion

While proton-boron fusion is considered 'aneutronic' (apparently aneutronic actually means that less than 1% of the energy produced is via neutrons) I believe that it is expected that proton-boron ...
5
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4answers
139 views

Why do stars undergo nuclear fusion?

This might sound silly. But we always talk about nuclear fusion in stars and I have always wondered why this process happens at all. Is it inevitable for fusion to happen at the temperature and ...
59
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3answers
8k views

Why didn't the Big Bang create heavy elements?

In the case of a supernova explosion it is possible to create heavy elements through fusion. Supernovae have a tremendous amount of energy in a very small volume but not as much energy per volume as ...
1
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1answer
45 views

Can the lithium test be applied to differentiate brown dwarfs from other substellar objects?

The lithium test is often used to differentiate brown dwarfs from low-mass M-type dwarfs (see e.g. Martin et al. (1994)), because brown dwarfs (at least the lower-mass ones) do not burn lithium, ...
9
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1answer
546 views

Do supernovae produce an appreciable amount of lithium?

David Z's answer to this question got me wondering - is any appreciable amount of lithium produced as the result of a supernova explosion, either by fusion (which seems unlikely to me, but I don't ...
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0answers
31 views

Do exotic states of matter have high fusion cross-sections?

The Lawson criterion suggests that a chain fusion reaction will only occur in a confined plasma. Since it's a product of temperature and pressure (or density) a chain reaction would be virtually ...
0
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2answers
111 views

How is hydrogen stored in hydrogen bombs?

Fusion bombs obviously fuse hydrogen atoms, using the pressure from a fission bomb. But how much hydrogen does it contain, and how is it stored? AFAIK hydrogen easily drops its electron and escapes as ...
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2answers
47 views

How much energy is released per unit mass from depressurizing degenerate matter?

A neutron star remnant consists mostly of neutron degenerate matter. If you happened to suddenly have 1 kg of it in your lap without the pressure necessary to keep it degenerate, I suppose it would ...
2
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1answer
82 views

Help identifying a Fusion approach

Several years ago, I saw a Google video (back before the YouTube acquisition) where the leader of a group studying an unusual approach to fusion gave a presentation. His approach centered on a ...
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1answer
61 views

Why do practical fusion reactions need more than one product?

The Wikipedia article about nuclear fusion says that To be a useful energy source, a fusion reaction must ... have two or more products: This allows simultaneous conservation of energy and ...
2
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3answers
641 views

Pure hydrogen star

What is the smallest mass of pure hydrogen that can ignite fusion? That is can population III stars have tiny masses? How would such stars develop? How long would such a star last?
2
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1answer
115 views

Using particle accelerators for nuclear fusion [duplicate]

Apologies this is probably a stupid idea but I am curious and my knowledge of physics is limited as I am 14. So I was wondering if we could use particle accelerators to achieve nuclear fusion. I have ...
0
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1answer
32 views

Plot of fusion energy output growth? [closed]

What would a chart of energy output of elements of mass X fused with hydrogen look like? What about X fused with X?
4
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1answer
106 views

Free neutrons in the sun's core?

In the standard description of proton-proton fusion, the first step of the interaction proceeds through the unbound diproton $\rm^2He$: $$ \begin{aligned} \rm p + p &\to \rm {}^2He^* \\ \rm ^2He^* ...
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4answers
310 views

Coupling fission and fusion and disappear all mass. Why doesn't this happen?

I'm confused about the fact that in a fission process the masses of the "products" are less than the mass of the "reactants". And in a fusion process the masses of the "products" are less than the ...
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3answers
589 views

Why do only heavy radioactive elements perform fission or fusion?

Why do only heavy radioactive elements perform fission or fusion? I mean what's so special about heavy elements which makes them ideal for nuclear fission? Also why do only neutrons show ...
1
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2answers
118 views

If planet like Jupiter is massive enough to hold hydrogen with its gravity is it bound to become a star?

I have been reading about Jupiter as of late and reason I am asking is if Jupiter has strong enough gravity to pull hydrogen to itself then it should be only matter of time when it will acquire enough ...
2
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1answer
121 views

Difference between fusion plasma and fluorescent lamp plasmas

How is the plasma in a compact fluorescent lamp (CFL) different from a plasma in say ITER or the sun? Why does ITER need 100MK and a CFL can work at practically room temperature (apart from the ...
1
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1answer
121 views

Are fusors a cost-effective source of helium?

It's not hard to imagine geology that didn't give us convenient concentrations of terrestrial helium, or that someday soon we'll have exhausted those natural sources. How cost-effective is existing ...
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2answers
293 views

Why more Fe-56 than Ni-62 as fusion product in heavy stars?

Suppose we create an Fe-56 nucleus and an Ni-62 nucleus, each from individual protons and neutrons. In the case of Ni-62, more mass per nucleon is converted to binding energy. Thus we could argue the ...