Pressures required for nuclear fusion

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Discussion Overview

The discussion revolves around the conditions necessary for achieving nuclear fusion, specifically the roles of pressure and temperature in the fusion process. Participants explore whether high pressures alone can facilitate fusion or if high temperatures are also essential, with a focus on the D-T (deuterium-tritium) fusion reaction.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Gabriele questions if fusion can be achieved solely through very high pressures at room temperature, or if both high pressures and high temperatures are necessary.
  • Some participants assert that while the Lawson criterion must be satisfied, achieving fusion typically requires both high pressures and high temperatures, although fusion may occur under certain conditions with only high pressure.
  • One participant mentions that laser fusion can achieve extremely high pressures without specific heating, suggesting a different approach to fusion.
  • Another participant emphasizes that compression of the fuel leads to heating, indicating that while high temperatures may not be a prerequisite, they often result from the compression process.
  • Gabriele acknowledges that high pressures can be sufficient for fusion, but notes that high temperatures often arise as a by-product of compression due to the fuel's behavior and equation of state.
  • A later reply introduces a question about the effects of adiabatic compression on solids, expanding the discussion to different states of matter.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of high temperatures for fusion. While some argue that high pressures alone can suffice, others maintain that high temperatures are typically involved due to the nature of the compression process. The discussion remains unresolved regarding the exact conditions required for fusion.

Contextual Notes

There are limitations in the discussion regarding the specific data for the D-T reaction cross-section as a function of pressure, and the implications of adiabatic compression on different states of matter are not fully explored.

g_mogni
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I know that to achieve fusion one has to satisfy the Lawson criterion. My question is: can fusion be achieved only by generating very high pressures but keeping the system at room temperature, or does it necessarily require a combination of both high pressures and high temperatures? If by some miraculous design one could apply a pressure of 1 Million Megabars to a tiny volume of D-T gas, would that be enough or are temperatures of millions of degrees also required? I can't find anywhere the data for the D-T reaction cross-section as a function of pressure but at room temperature...

Thanks,

Gabriele
 
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g_mogni said:
I know that to achieve fusion one has to satisfy the Lawson criterion.
Only for self-sufficient fusion without continuous heating. But you have to get at least close to it to get relevant fusion.

There is no realistic way to get a high pressure without a high temperature on any reasonable timescale, but eventually you'll get fusion even in that case.
 
Laser fusion uses extremely high pressure, without any particular heating.
 
The compression still heats up the fuel.
 
mfb said:
The compression still heats up the fuel.
You are right. The point I was trying to make is that the fuel is not heated for the fusion to take place. The compression is the main mechanism.
 
Thank you for you replies. I therefore understand that high-temperatures are not a pre-requisite for fusion to take place, high-pressures alone can be enough, but often high temperatures are a by-product of the high-pressure compression due to the way the fuel capsule behaves and its equation of state...

G
 
When ideal gas is adiabatically compressed, the ratio of final and initial temperature is determined by the compression ratio, and independent of the initial temperature.

What happens when a solid is adiabatically compressed?
 

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