# Pressures required for nuclear fusion

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## Main Question or Discussion Point

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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mfb
Mentor
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.

mathman
Laser fusion uses extremely high pressure, without any particular heating.

mfb
Mentor
The compression still heats up the fuel.

mathman
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?