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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33
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3answers
27k views

Origin of elements heavier than Iron (Fe)

In all the discussions about how the heavy elements in the universe are forged in the guts of stars and especially during a stars death, I usually hear that once the star begins fusing lighter atoms ...
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10answers
33k views

Can Jupiter be ignited?

Our solar system itself contains two candidate "Earths" One is Jupiter's moon Europa and another is Saturn's moon Titan. Both of them have the problem of having at low temperature as Sun's heat ...
12
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4answers
10k views

Could we use particle colliders as fusion generators?

So I know the basic gist is that fusion power's main issue is sustaining the fusion. I also know that there are two methods. The Torus method and the laser method. The torus magnetically contains ...
10
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2answers
10k views

How to explain $E=mc^2$ mass defect in fission/fusion?

What is the nature of nuclear energy? This is closely related to the correct explanation of mass defect. I did some research of that topic and cannot come to a single comprehensive and consistent ...
26
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3answers
20k views

Why is the nucleus of an Iron atom so stable?

Lighter nuclei liberate energy when undergoing fusion, heavier nuclei when undergoing fission. What is it about the nucleus of an Iron atom that makes it so stable? Alternatively: Iron has the ...
12
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2answers
3k views

With what probability does nuclear fusion occur at energies far below the Coulomb barrier?

Even at the core of the sun, the temperature of $\sim 10^7$ K only results in $kT\sim1$ keV, which is about a thousand times less than the electrical potential energy of $\sim1$ MeV needed in order to ...
13
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4answers
16k views

Why can't Iron fusion occur in stars?

It is said that iron fusion is endothermic and star can't sustain this kind of fusion (not until it goes supernova). However star is constantly releasing energy from fusion of elements like Hydrogen ...
11
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3answers
2k views

Proton - neutron fusion?

In reviewing some problems in an elementary book, I ran across a reference to the reaction $p+n\rightarrow d$ + "energy". Is that possible? I don't see any reason why not, but I don't find any ...
4
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5answers
11k views

How much iron would I have to shoot into the Sun to blow it up?

My understanding--though it's from a Science Channel show so I'm not sure if it is correct--is that there is a fusion reaction happening in the center of the sun. Atomic nuclei are being created and ...
6
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2answers
7k views

Fusion: Why deuterium and tritium?

I would like to know why scientists try to use deuterium and tritium for fusion and not just the ordinary isotope of Hydrogen ${}^1H$?
15
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3answers
11k views

What would be the characteristics of Jupiter if it shrank?

So, I've heard from various works of science fiction about the prospect of turning Jupiter into a star. From what I know about the physics of such a task, it would require somehow condensing Jupiter ...
4
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2answers
2k views

Is the E-cat by Andrea Rossi et al. for real?

Does this thing really do what they say? http://www.youtube.com/watch?v=EhvD4KuAEmo If it does, it looks like this will probably be the biggest breakthrough in science ever :)
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2answers
1k views

Fusion vs. Fission

I understand why fission generates large amounts of energy when the nucleus is split, but then why does fusion generate such large amounts of energy. If fission releases energy when some mass is lost ...
100
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11answers
17k views

Why do fusion and fission both release energy?

I only have high school physics knowledge, but here is my understanding: Fusion: 2 atoms come together to form a new atom. This process releases the energy keeping them apart, and is very energetic. ...
31
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1answer
3k 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 ...
13
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3answers
6k views

Why does fusion stop at iron when nickel is most tightly bound?

My understanding is that stellar fusion naturally stops at iron because it is energetically unfavourable to grow the nucleus further. But iron is only the third most tightly-bound nucleus, nickel is ...
10
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2answers
4k views

Nuclear Fusion with extremely high pressure and low temperature

Theoretically, if we just create a high pressure with low (room 20C) temperature, at some point nuclear fusion can be started. Is there any research on this topic, how high should be this pressure ...
9
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3answers
2k views

Can the High beta fusion reactor work?

Are the claims made about the http://en.wikipedia.org/wiki/High_beta_fusion_reactor realistic? Can such a small fusion reactor really work?
9
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2answers
1k 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 ...
6
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4answers
4k views

How much of the energy from 1 megaton H Bomb explosion could we capture to do useful work?

The world is full of nuclear warheads being stockpiled. Controlled fusion power seems a long way away. Could we put these warheads to better use by exploding them in a controlled way and capturing ...
6
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2answers
1k views

How much faster is the fusion we make on earth compared to the fusion that happens in the sun?

I have come across many websites that states that the proton-proton fusion which is the dominant type of fusion that powers the suns, is extremely slow and that is why the sun is still burning to that ...
23
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2answers
3k views

When did the first carbon nucleus in the Universe come into existence?

I am a chemist with a passion for astrophysics and particle physics, and one of the most marvellous things I have learned in my life is the process of stellar nucleosynthesis. It saddens me how my ...
8
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3answers
14k views

Why only light nuclei are able to undergo nuclear fusion not heavy nuclei?

Is it because of the binding energy or the binding energy per nuclei . I am having trouble with this whole binding energy and nuclear fusion concept.
13
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3answers
4k views

How often does nuclear fusion occur within the human body?

I'm just curious. I figure atoms fuse occasionally just by chance, like quantum tunneling or rogue waves. Is this true? If so, any idea how often?
4
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4answers
12k views

How is energy extracted from fusion?

I understand that combining deuterium and tritium will form helium and a neutron. There are three methods to do this (1) tokamak (2) lasers and (3) cold fusion. I would like to know after helium is ...
16
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1answer
811 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 ...
11
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3answers
1k views

Concentrating Sunlight to initiate fusion reaction

The idea is to collect sunlight over a large area, and concentrate it down to the nano scale. For the sake of discussion lets say you concentrate all the light you collect down to 1000 nanometers (1µm)...
8
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2answers
2k views

What elements can be created in the fusion process of different types of stars?

As I understand it fusion inside a sun can produce heavier and heavier elements until some sort of "nucleus size limit" is reached. As far as I understand, the limit is thought to be reached with the ...
10
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1answer
147 views

How many times do solar protons repeatedly fuse and fission before they form deuteron

In the proton-proton chain reaction in the Sun, the first step is $$p + p \rightarrow \; ^2_2{\rm He} .$$ After this, the most likely thing to happen next is that the reverse reaction occurs: the $^...
14
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4answers
12k views

Can open, unsafe nuclear fusion reaction burn the atmosphere?

I happened to hear people saying that the nuclear fusion bomb tests could set the atmosphere on fire. I have some serious doubts about that - but I have no facts. Nuclear fusion reaction requires $15*...
16
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1answer
2k views

Can nuclear fusion alone account for the energy output from type 1a supernova?

Unlike other supernova, which can vary in their size, Type Ia supernova are all about the same size. This is due to the fact that they are caused when a white dwarf star gains enough mass from its ...
7
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1answer
9k 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 ...
5
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3answers
8k views

Light formed by the sun?

This is an extract from the astrophysics chapter in my book: Hydrogen atoms fuse to form helium. At the same time, lots of of gamma photons and neutrinos are produced. The photons take thousands ...
3
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5answers
5k views

Why do almost all nuclear reactions release energy?

I'm just wondering why almost all nuclear reactions release energy, in a typical way, the mass defect is transformed into energy ? Is there a nuclear reaction that gains mass (resp. energy)? or most ...
2
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1answer
1k views

Help with Modeling a Liquid Vortex. (Related to General Fusion)

I want to model liquid lead swirling in a sphere. This is connected to General Fusion’s fusion machine. A 55 million dollar, Jeff Bezos funded, 60 person company trying to change the world with ...
0
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2answers
189 views

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 =...
11
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1answer
498 views

Does tritium hydride exhibit measurable spontaneous fusion via proton tunneling?

In a fascinating 30 June 2013 article in Nature Chemistry, researchers from the University of Leeds found that when molecules of hydroxyl (OH, a fairly stable radical) and methanol (CH$_3$OH) are cold ...
3
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2answers
450 views

Fusion reactors why does size matter?

I've been following articles about fusion recently, and with the ITER project mostly. I have noticed that their view point is they need to build a large scale reactor in order to achieve their goals. ...
2
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1answer
338 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
401 views

Can Hydrogen Fusion via CNO Cycle Occur in First Generation Stars

CNO cycle requires the presence of carbon, nitrogen and oxygen to undergo hydrogen fusion. Does this mean that for first generation stars, no matter how big they are, can't undergo hydrogen fusion by ...
0
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3answers
371 views

How does gravity cause nuclear fusion in stars?

I am a bit confused regarding the nuclear fusion that occurs during star formation. For example, suppose there is a huge hydrogen cloud. It gets more mass and therefore pulls in more and more hydrogen,...
11
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2answers
8k views

Why is Helium-3 better than Deuterium for fusion energy production?

I see that many websites and magazines with physics thematic are pretty excited about mining Helium 3 isotope on the Moon. But this seems to be a very hard-to-get resource. For more than one reason: ...
6
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2answers
595 views

How are our enzymes able to perform quantum tunnelling?

The hydrogen protons undergo quantum tunnelling in the the sun to fuse into helium, but are only able to do so as they are under immense heat and pressure and the protons and electrons get separated. ...
4
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2answers
14k views

What is the lowest possible theoretical temperature that nuclear fusion can occur at?

I am not talking about the pseudo-science of so called cold fusion I am interested in what temperature you can get away with to produce fusion reaction. I was thinking in terms of micro-fusion or at ...
3
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2answers
7k views

What is the shielding in nuclear reactors mainly against?

I have a little knowledge about ionizing radiation and I have been confused over why nuclear reactors need these massive shields. So, if I am not mistaken, Alpha and Beta radiation are not that ...
2
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1answer
666 views

Can Antimatter undergo nuclear fission/fusion?

I was curious if antimatter could undergo nuclear fission/fusion with other antimatter. It makes sense, I was wondering if it would work?
0
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0answers
119 views

Discussion about a new nuclear fusion design [duplicate]

this company is running a similar project described below. https://firstlightfusion.com/technology/#our-approach Let me clarify here, this is not cold fusion. D&T gas will be compressed very ...
98
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4answers
33k views

Would a pin head heated to 15 million degrees Celsius kill everyone in a 1000 mile radius?

The YouTube video How Hot Can it Get? contains, at the 2:33 mark, the following claim: A pin head heated to 15 million degrees will kill everyone in a 1000 miles radius. On what basis can this ...
36
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3answers
4k views

Nuclear Fusion: Why is spherical magnetic confinement not used instead of tokamaks in nuclear fusion?

In nuclear fusion, the goal is to create and sustain (usually with magnetic fields) a high-temperature and high-pressure environment enough to output more energy than put in. Tokamaks (donut shape) ...
14
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2answers
1k views

How large can you make a tokamak?

I've seen questions on how small you can make a tokamak. But I haven't yet seen any "physical" upper limit on the tokamak design. If you take a wind turbine for example, doubling the linear ...