Questions about fusion (from a high-schooler)

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Discussion Overview

The discussion revolves around nuclear fusion as a potential power source, focusing on the mechanics, reactions involved, and the challenges associated with containment and energy production. Participants explore various aspects of fusion, including the types of reactions, energy calculations, and the implications of waste products.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Ibrahim expresses confusion about the concept of containment for fusion and asks if it is true that no substance on Earth can contain it.
  • Some participants clarify that fusion requires extreme conditions and that solid materials cannot contain the reaction due to the high temperatures involved.
  • There is a discussion about the waste products of fusion, with some stating that helium-4 is produced, while others note that there are radioactive waste products, albeit less than from fission reactors.
  • Participants debate the energy output of fusion reactions, particularly the D + T reaction, and how it compares to other energy sources, including matter-antimatter annihilation.
  • Ibrahim questions the calculations related to energy production from fusion and the mass defect involved in the reactions.
  • There is mention of the instability of He-5 in the fusion process and inquiries about where the energy goes during its decay to He-4 and a neutron.
  • Some participants discuss the concept of a "blanket" in fusion reactors and the role of confinement in maintaining the plasma state necessary for fusion.
  • Ibrahim asks about the nature of plasma and how it is created from deuterium, seeking clarification on its necessity for fusion.

Areas of Agreement / Disagreement

The discussion contains multiple competing views and remains unresolved on several points, particularly regarding the nature of waste products and the specifics of energy calculations in fusion reactions.

Contextual Notes

Participants express uncertainty about the definitions and implications of terms such as "mass defect" and "plasma," and there are unresolved questions about the energy dynamics in fusion reactions.

Who May Find This Useful

This discussion may be useful for high school students, educators, and anyone interested in the fundamentals of nuclear fusion and its potential as an energy source.

  • #31
aquitaine said:
This seems (at least from my POV) to be a really low tech and inefficient way to turn the heat into actual work. The turbine method was invented in the 19th century, surely there must be a more advanced method for getting work out of it. The Tokamak operates on plasmas, maybe that could be utilized somehow.
Well, nuclear systems generate thermal energy, so they are a fancy way to generate heat, which is usually transferred to a working fluid. The working fluid(s) transfer energy and momentum to turbomachinery, which is used to drive a generator to produce electricity.

In the case of a plasma, two possibilities are extracting energy directly from the plasma as it expands against the magnetic field, or use charge separation. The strategy depends on the system geometry, i.e. plasma confinement and magnetic field configuration.
 
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  • #32
In the case of a plasma, two possibilities are extracting energy directly from the plasma as it expands against the magnetic field, or use charge separation. The strategy depends on the system geometry, i.e. plasma confinement and magnetic field configuration.

How much energy can we theoretically get out of a system like this? How much more (or less) efficient is it?

Well, nuclear systems generate thermal energy, so they are a fancy way to generate heat, which is usually transferred to a working fluid. The working fluid(s) transfer energy and momentum to turbomachinery, which is used to drive a generator to produce electricity.

True, and so for fission there isn't anyother way. But fusion doesn't just make steam, it makes plasma and so maybe we can use that directly instead of having to go through working fluids.
 

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