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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148 views

At what rate do I need to accelerate for my car to become a fusion reactor?

I was sitting on the bus on my way home, and this popped into my mind. As a car accelerates, the air pressure at the back of the car increases as air is pushed back due to inertia. This pressure will ...
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102 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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Dangers of controlled fusion temperatures

I've been looking for an answer to this question for some time, and I apologize in advance for my lack of general knowledge on the subject matter. I can't wrap my head around how we can have ...
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1answer
89 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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137 views

Solar Power Fusion

Would it be possible through a clever arrangement of solar dishes, lenses and mirrors etc, to create fusion at the focal point? Imagine you arrange your solar dishes, lenses and mirrors in such a way,...
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144 views

Could tidal effects make matter hot enough for nuclear fusion?

There was a recent question about cosmological firewalls. Putting aside questions of entanglement and information and looking at the problem from a pure mechanical viewpoint, we know that although ...
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47 views

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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207 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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1answer
475 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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633 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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348 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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1k 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 ...
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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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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 ...
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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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85 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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321 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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231 views

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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871 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
164 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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171 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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138 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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Can we observe solar p-p fusion reaction somehow on Earth?

What are the properties of proton+proton fusion reaction $p + p → 2H + e^+ + ν_e + 0.42 MeV$ 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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779 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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215 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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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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Could you know in advance specifically when a star will go supernova?

I've been thinking about star trek 2009 and star trek Picard in which they happen to talk about a sun inside a fictional solar system which goes supernova destroying a particularly important planet to ...
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82 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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852 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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245 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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154 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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362 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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56 views

Sun's energy and grand unification

According to Wikipedia, The approximate grand unification energy value is equal to $1×10^{25}$ eV or $10^{16}$ GeV This is equal to $1602176$ J. Now, The Earth receives 174 petawatts (PW) ...
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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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161 views

How does the Sun generate its energy?

We all know that the sun generates its energy from nuclear fusion in the core. The electromagnetic radiation produced slowly travels upwards, while constantly being absorbed and re-emitted by the ...
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1answer
77 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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102 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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70 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 bomb, we can collect the energy, like laser nuclear ...
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4k views

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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155 views

How do we know which lighter elements fuse to form heavier elements?

Formation of lighter elements is fairly straightforward: $^4$He + $^4$He + $^4$He = $^{12}$C. However for each heavier element (heavier than Fe in particular), is there exactly one combination of (...
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Why do only red dwarf stars have convective currents?

Stellar models indicate that red dwarfs less than 0.35 M☉ 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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256 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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1k views

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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720 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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691 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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105 views

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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