Control Fusion Reaction: Difficulties & Possibilities

In summary, the main difficulty in controlling the fusion reaction is containing the plasma in a stable form at extremely high temperatures and pressures. Walls made of matter cannot withstand the heat generated by fusion, and even if they could, the plasma would push back on the magnetic field used for confinement. While implosion could compress the plasma, the resulting outward pressure would put stress on the confinement system. Additionally, the density and pressure of the plasma must be carefully balanced for successful fusion, making the process complex and challenging to achieve on a commercial scale.
  • #1
ahsan999
1
0
why it is so difficult for scientist to control the fusion reaction
why they not make a lage room with heat resistance walls and make a explosion to start the fusion reaction and add appropiate amount of hydogen by some hole
if small quantity of hydrogen is entered in such room so the energy produced will be contol able
if this is not possible try to conveince me as early as possible
 
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  • #2
The problem is one of containing the plasma in a stable form such that the fusion reaction can progress at controlled rate.

An explosion is essentially a pressure wave, so it would be difficult to feed hydrogen into and explosion. Chemical explosions are very low temperature compared to plasma temperatures.

I think one means implosion, which would compress a plasma. But then what goes in (inward) generally comes back out, and if energy is generated within the imploded mass, the outward pressure would be much greater than the inward pressure and that would put a lot of stress on the magnetic confinement system.

In the case of inertial confinement, it's practicality has yet to be demonstrated. That involves a sequence of microimplosios/microexplosions of fusion targets, with hopefully more energy (thermal energy) generated by the explosion than went into the implosion.

Based on the statement, "if small quantity of hydrogen is entered in such room so the energy produced will be contol able," it is apparent that one does not understand the physics of fusion or plasma confinement.
 
  • #3
ahsan999 said:
why they not make a lage room with heat resistance walls and make a explosion to start the fusion reaction

The temperature needed to generate sufficient energy by nuclear fusion is so high that no walls made of matter can withstand it. Any "heat resistant walls" would be vaporized by the high temperatures.
 
  • #4
phyzguy said:
The temperature needed to generate sufficient energy by nuclear fusion is so high that no walls made of matter can withstand it. Any "heat resistant walls" would be vaporized by the high temperatures.
That's part of it.

Fusion takes place at temperatures (kinetic energies) of 50-200 keV, and 1 keV = 11605000K. So that's 500 million K to 2 billion K.

The other part is the density of the plasma, and the fact that P = nkT. Even if the plasma is confined magnetically from any material wall, one has to balance that with the enormous pressures.

Terrestrial fusion plasmas confined in a magnetic field operate in essentially a vacuum with particle densities on the order of 1014 cm-3. Inertial confinement targets can achieve higher densities than 1022 cm-3, but the confinment time is on the order of microseconds.
 
  • #5
Astronuc said:
That's part of it.

The other part is the density of the plasma, and the fact that P = nkT. Even if the plasma is confined magnetically from any material wall, one has to balance that with the enormous pressures.

Terrestrial fusion plasmas confined in a magnetic field operate in essentially a vacuum with particle densities on the order of 1014 cm-3.

But the pressure in and of itself isn't really a big problem. For n=10^14 cm^-3, T=200 keV, we would have a pressure of about 30 atmospheres, which would be easily confined by a steel pressure vessel. Bear in mind that with magnetic confinement fusion the pressure of the plasma ultimately needs to be borne by a mechanical structure anyway. If it weren't for the fact that the steel pressure vessel would vaporize, fusion would be easy. You could just fill a steel vessel with a D-T gas and pump heat into it until it ignited.
 
  • #6
Without a magnetic confinement, the steel vessel would quench the plasma. There is not enough mass in a plasma to melt the steel. The problem of the plasma pressure is the push back on the magnetic field, as well as the magnetic field strength, B, required to confine the plasma, which determines the current necessary to produce the magnetic field.

Did the pressure calculation also include the electron pressure in addition to the nuclei? The 1014 is just an order of magnitude. Double the value, double pressure; quadruple the number, quadruple the pressure; . . .

It's matter of balancing power density, pressure, and other system requirements.

If it was so easy, we would have had a viable commercial fusion plant 20+ years ago.
 

1. What is a fusion reaction?

A fusion reaction is a process in which two or more atomic nuclei combine to form a heavier nucleus, releasing a large amount of energy in the process.

2. Why is controlling a fusion reaction difficult?

Controlling a fusion reaction is difficult because it requires extreme temperatures and pressure to overcome the natural repulsion between positively charged nuclei. This requires sophisticated technologies and materials that can withstand these extreme conditions.

3. What are some challenges in achieving a sustainable fusion reaction?

There are several challenges in achieving a sustainable fusion reaction, including finding a way to confine the plasma at high enough temperatures and pressures for a sustained period of time, developing materials that can withstand the extreme conditions, and finding a way to efficiently extract the energy produced.

4. What are some potential benefits of achieving a successful fusion reaction?

If a successful fusion reaction can be achieved, it could provide a nearly limitless source of clean energy with no greenhouse gas emissions. It could also potentially provide a solution to the world's energy crisis, as fusion fuel sources are abundant and easily accessible.

5. What are some current efforts and progress in achieving a controlled fusion reaction?

There are several research projects and experiments currently underway to achieve a controlled fusion reaction, including the International Thermonuclear Experimental Reactor (ITER) in France and the Joint European Torus (JET) in the United Kingdom. While significant progress has been made, there is still much work to be done before a sustainable fusion reaction can be achieved.

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