Pressures required for nuclear fusion

In summary, when trying to achieve fusion, the Lawson criterion must be satisfied. There is no realistic way to achieve high pressure without high temperature in a reasonable timeframe, but eventually fusion can occur even with just high pressure. In laser fusion, high pressure is achieved without adding additional heat, as the compression itself heats up the fuel. However, in general, high temperatures are often a byproduct of high pressure compression due to the behavior of the fuel and its equation of state. When an ideal gas is adiabatically compressed, the final and initial temperatures are determined by the compression ratio and are independent of the initial temperature. When a solid is adiabatically compressed, a similar process occurs.
  • #1
g_mogni
48
0
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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  • #2
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.
 
  • #3
Laser fusion uses extremely high pressure, without any particular heating.
 
  • #4
The compression still heats up the fuel.
 
  • #5
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.
 
  • #6
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
 
  • #7
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?
 

1. What is the minimum pressure required for nuclear fusion to occur?

The minimum pressure required for nuclear fusion to occur is about 100 million atmospheres or about 100 GPa (Gigapascals). This pressure is necessary to overcome the repulsive force between the positively charged nuclei and initiate the fusion reaction.

2. How do scientists create the necessary pressure for nuclear fusion?

Scientists use powerful lasers or magnetic fields to compress and heat the fuel, typically a mixture of hydrogen isotopes, to the required pressure and temperature for fusion to occur. This is known as inertial confinement fusion or magnetic confinement fusion.

3. Can the pressure for nuclear fusion be sustained for a long period of time?

Currently, sustained nuclear fusion reactions have not been achieved due to the immense pressure and temperature requirements. However, scientists are working on developing advanced fusion reactors that can sustain the necessary conditions for longer periods of time.

4. Are there any risks associated with the high pressures involved in nuclear fusion?

The high pressures involved in nuclear fusion can be dangerous if not carefully controlled. For example, in magnetic confinement fusion, sudden disruptions in the plasma can lead to high energy bursts that can damage the reactor. However, extensive safety measures are put in place to mitigate these risks.

5. What are the challenges in achieving the necessary pressures for nuclear fusion?

The main challenge in achieving the necessary pressures for nuclear fusion is to create a self-sustaining reaction, where the energy produced by the fusion process is enough to maintain the high pressures and temperatures required. Another challenge is finding suitable materials that can withstand the extreme conditions inside a fusion reactor.

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