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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Why this arrangement of thingys in this light-induced fusion reactor?
Here is a photo from inside a light-induced fusion reactor at the National Ignition Facility, California.
Image source: Wikipedia
I'm not sure what those thingys all around it are but I assume they ...
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185 views
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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413 views
How to calculate the bremsstrahlung limit in the fusion triple product diagram?
The fusion triple product is a commonly used figure of merit to quantify the progress in fusion research, it is the product of plasma density $n$, temperature $T$ and energy confinement time $\tau_E$....
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591 views
Can heavy elements be fused? [duplicate]
Yes, I know, in stars, fusion occurs up to Iron(-56); but, I want to know if fusion past this nucleus can happen at all.
If so, the daughter element would move to the right of the peak and its ...
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94 views
Could there be a rocky star, made from silicon, oxygen, etc?
Rocky in terms that it will have mostly silicon and oxygen composition, just like terrestrial planets. But not because it runs out of hydrogen and helium, rather it should start it's life by fusing ...
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338 views
Learning resources for computational plasma physics
I'd like to try implementing a "simple" simulation of nuclear fusion (http://en.wikipedia.org/wiki/Nuclear_fuel_cycle) process taking place inside an idealized reactor. Are there any good resources (...
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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 ...
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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 ...
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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 ...
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Intermediate product of CNO cycle
CNO cycle of stellar nucleosynthesis involves several steps in which different isotopes of Carbon, Nitrogen, and Oxygen are transmuted into each other when hit by a ...
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1answer
80 views
What is the shortest duration fusion reaction?
In a tokamak fusion reactor fusing hydrogen nuclei what is the shortest duration experiment that successfully fused nuclei.
Is there a database with fusion reactions and their duration.
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316 views
Simulation of plasma in tokamak
I am reading some papers on numerical algorithms for simulation of plasma in the context of nuclear fusion in a tokamak. I am getting a little lost as there is a huge number of references, and it is ...
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Are Lockheed Martin nuclear fusion claims realistic? [duplicate]
Lockheed Martin reported breakthroughs on nuclear fusion technology for energy. Are these claims scientifically realistic?
The claims have been reported in the media: http://www.nbcnews.com/science/...
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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?
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856 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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1answer
150 views
Where is nuclear fusion occuring in the Sun?
My understanding is that the sun is basically a sphere of hydrogen with a helium core, and that the hydrogen is undergoing nuclear fusion to produce helium.
There are many images and cross-sectional ...
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148 views
Is high temperature **required** for nuclear fusion?
Tl;dr: Can fusion be achieved only by speeding up particles to high enough speeds to smash into each other?
I know that it is necessary for protons, or any oppositely-charged particles for that ...
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121 views
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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103 views
Can we observe solar p-p fusion reaction somehow on Earth?
What are the properties of proton+proton fusion reaction
$p + p ā 2H + e^+ + Ī½_e + 0.42 MeV$
making it hard to replicate on Earth?
If we aim beam of protons to a can of water, won't we observe ...
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761 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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718 views
Can Deuterium undergo a nuclear fusion without the presence of Tritium?
I've been reading about fusion fuels for a while now, and I understand that in Lithium-Deuterium fuel, the neutrons from the fission reaction bombard the Lithium to produce Tritium and the D-T ...
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1answer
211 views
How is/do they plan on having fusion energy collected at the National Ignition Facility?
I was just watching a program on television showing how the method they use at the National Ignition Facility to attempt to achieve fusion is to fire extremely powerful lasers at a small pellet of ...
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1answer
516 views
How much energy can be extracted from hydrogen?
http://en.wikipedia.org/wiki/B-L says that the difference between baryon number and lepton number is conserved. Ordinary hydrogen has one of each, but turning it into helium releases only the binding ...
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81 views
How does the $p+p + e^-\rightarrow D + \gamma\gamma+ \nu$ reaction proceed in the sun?
In this video on nuclear fusion the explanation of the reaction $p+p\rightarrow D + \nu + \gamma\gamma$ is that the two protons collide, form a weakly bound state, and then sometimes decay into the ...
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Binding energy, fission and fusion
My high school physics book doesn't elaborate the idea of binding energy and how it's related to fission and fusion adequately in a way that made me have wrong thoughts about these ideas.
What i ...
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1answer
754 views
Why does resistance decrease as the temperature increase in plasma?
I am writing about Ohmic heating as a heating method for fusion for a class in school. But I wonder why the resistance decreases as the temperature increases in the plasma? This seems odd because ...
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231 views
In a fusion reactor like Tokamak, how is fuel injected without destroying the fuel injector? [closed]
Plasma temperatures in a tokamak are around 100 million C.
Presumably for a power plant that will run for a long period of time, fuel will have to be injected and "burnt" products will have to be ...
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151 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
335 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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445 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.
...
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1answer
54 views
Sun's energy and grand unification
According to Wikipedia,
The approximate grand unification energy value is equal to $1Ć10^{25}$ eV or $10^{16}$ GeV
This is equal to $1602176$ J.
Now,
The Earth receives 174 petawatts (PW) ...
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2answers
104 views
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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Why can't two hydrogen atoms be slowly “pressed together” (fused to form helium) with some advanced device (not collided at high speed)?
I apologize for my lack of physics knowledge, and I won't be gaining much any time soon, since I'm focusing mostly on work and physical exercise. I can't help but wonder about this:
Questions:
...
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The amount of energy required to break the Coulomb Barrier
This web page says that only 3-10 keV of energy is required to break the Coulomb barrier for colliding hydrogen nuclei.
Pretty far from what originally said.
Is this true? Does this have something ...
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1answer
58 views
Why do tokamaks and most other fusion reactors use neutral plasmas?
Most experimental fusion reactors use quasi-neutral plasma as the working substance. However, there are numerous advantages to using a non-neutral plasma:
Ease of confinement. Pure proton gases have ...
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1answer
70 views
Evolution of red dwarf stars
While low mass stars (initial mass approximately $0.1 M_\odot$ to $0.8 M_\odot$) are quite numerous, their evolution seems to draw relatively little attention. The lower central density and ...
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1answer
67 views
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 bombļ¼ we can collect the energy, like laser nuclear ...
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How many times does plasma do a full loop tokamak before fusion?
From this photo I assume the plasma is also moving in a loop through the reactor due to it being a charged particle.
I have been trying to find a speed at which it does this but couldn't and neither ...
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910 views
Why do only red dwarf stars have convective currents?
Stellar models indicate that red dwarfs less than 0.35 Mā are fully convective.[3] Hence the helium produced by the thermonuclear fusion of hydrogen is constantly remixed throughout the star, avoiding ...
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253 views
Why is there such an interest in Helium-3 and Moon mining?
A simple Google search reveals dozens of articles about the clean fusion energy that can be obtained from Helium-3. As Helium-3 is highly scarce on Earth, there are many spectacular schemes for ...
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How much potential fusion energy is in Earth's ocean?
Assuming the most efficient manner for extraction, and a ready supply of other necessary materials not mentioned herein, and given the current estimates about the volume of Earth's ocean, how much ...
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1answer
609 views
How long does it take plasma to radiate its heat?
Lets say we have 1 gram of plasma (Argon) at 1 million kelvin confined in a vacuum with electromagnets. If we keep the magnets on but shut down the device that heated the plasma, how long will it take ...
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662 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?
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1answer
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Could one “build” elements?
I was wondering this: would it be possible to "construct" elements by arranging their constituent particles in high-energy environments? So apart from just fusion, could you sub-atomically manufacture ...
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1answer
60 views
What can be learned from Wendelstein 7-x experiment?
This experiment achieved a stable plasma for 26 seconds.
What do we learn from it in general(why it was done)? and specifically about the possibility of achieving positive energy flow ($Q>1 $) by ...
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1answer
56 views
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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1answer
171 views
How long does it take for fusion to occur in a tokamak?
Once the plasma is in the tokamak reactor how long does it take until fusion starts to begin? I found that it must reach 150000000 degrees so, how long does it take for the plasma to reach this ...
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217 views
Nuclear Fusion Fuels
I have seen some possible fuels for nuclear fusion.
My questions are:
Are there other fuels available even theoretically or the list of candidates is limited?
What are the requirements that a "...
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152 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, ...
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Is man-made Carbon Fusion possible?
In a type Ia Supernova, the carbon accumulated in the earlier stages of a stars death fissues to create even heavier elements. Could this be used by humans aswell? Is it theoretically possible to ...
