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Chinese Tokamak reaches over 100M degrees

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Re: Chinese Tokamak reaches over 100M degrees

#3
A tokamak is a kind of fusion reactor, and basically the most prevalent.

"100M degrees" (Kelvin) corresponds to 10 KeV (kilo electron volts), which is an important figure to exceed for D-T fusion. D-T fusion which is the kind of fusion the ITER Tokamak (a forthcoming fusion reactor and international megaproject) intends to demonstrate.

An older fusion experiment, JET (Joint European Torus) reached these levels, so this does not break new ground, but it is important if this Chinese Tokamak is going to provide data useful for ITER.

I will note that it's rather unusual to refer to plasma temperature in Kelvin rather than in KeV. I edited this comment with a few more details to try to make it easier for laypeople to understand.

Re: Chinese Tokamak reaches over 100M degrees

#5
Okay, did some search:

- When two hydrogen nuclei combine, they produce an enormous amount of energy. That process is known as nuclear fusion.

- Light nuclei have to be heated to extremely high temperature, it is challenging to create a controlled, safe fusion reactor that offers more energy than it consumes. Once we have such we’d have a near-limitless source of clean energy.

- Nuclear fusion does produce radioactive waste. However, in contrast to fission produced wastes, they are short lived and decay to background levels in a very short time.

- Tokamaks try to do just that.

Re: Chinese Tokamak reaches over 100M degrees

#6

A tokamak is a kind of fusion reactor, and basically the most prevalent. "100M degrees" (Kelvin) corresponds to 10 KeV (kilo electron volts), which is an important figure to exceed for D-T fusion. D-T fusion which is the kind of fusion the ITER Tokamak (a forthcoming fusion reactor and international megaproject) intends to demonstrate. An older fusion experiment, JET (Joint European Torus) reached these levels, so th…

What important happens at that temperature?

Re: Chinese Tokamak reaches over 100M degrees

#7

A tokamak is a kind of fusion reactor, and basically the most prevalent. "100M degrees" (Kelvin) corresponds to 10 KeV (kilo electron volts), which is an important figure to exceed for D-T fusion. D-T fusion which is the kind of fusion the ITER Tokamak (a forthcoming fusion reactor and international megaproject) intends to demonstrate. An older fusion experiment, JET (Joint European Torus) reached these levels, so th…

You seem to know what you're talking about - do you know what the end goal of the work in this field is? Is it working towards nuclear fusion as an energy source?

Re: Chinese Tokamak reaches over 100M degrees

#8
post #6

A tokamak is a kind of fusion reactor, and basically the most prevalent. "100M degrees" (Kelvin) corresponds to 10 KeV (kilo electron volts), which is an important figure to exceed for D-T fusion. D-T fusion which is the kind of fusion the ITER Tokamak (a forthcoming fusion reactor and international megaproject) intends to demonstrate. An older fusion experiment, JET (Joint European Torus) reached these levels, so th…

What important happens at that temperature?

As I understand, this represents sufficient energy to overcome the Coulomb Barrier [1] which naturally repels atoms apart. To cause fusion, you need to push particles together either hard enough or fast enough that they push through this repulsion and fuse. The repulsion is a product of the electrostatic repulsion of the positive charges of the nuclei (pushing the positive ends of two magnets together, essentially).

The temperature of a gas is essentially a measure of the constituent particles' kinetic energy. Higher kinetic energy = higher temperature. 10keV represents enough kinetic energy for the D-T atoms to collide fast enough that they overcome the Couloumb repulsion and fuse together.

[1]: https://en.wikipedia.org/wiki/Coulomb_barrier

Re: Chinese Tokamak reaches over 100M degrees

#9
post #6

A tokamak is a kind of fusion reactor, and basically the most prevalent. "100M degrees" (Kelvin) corresponds to 10 KeV (kilo electron volts), which is an important figure to exceed for D-T fusion. D-T fusion which is the kind of fusion the ITER Tokamak (a forthcoming fusion reactor and international megaproject) intends to demonstrate. An older fusion experiment, JET (Joint European Torus) reached these levels, so th…

What important happens at that temperature?

You overcome the natural repulsion between deuterium and tritium and fuse them together.

Re: Chinese Tokamak reaches over 100M degrees

#10
The main challenge in working with these high temperature plasmas is confinement. In order to achieve nuclear fusion matter needs to be heated to immense temperature, so that the kinetic energy of nuclei colliding can overcome the electrostatic force of the protons pushing each other away and "fuse" into larger nuclei (held together by the "strong force"), converting a fraction of the reaction mass into a relatively large amount of energy in the process.

In order to keep the plasma at the temperatures where fusion can occur, rather extreme measures have to be taken. In the Tokamak approach, the plasma is placed in a toroidal vacuum chamber, and "suspended" in the center of the torus by using electromagnets that line the Tokamak chamber's walls. At such high temperatures the plasma is so energetic that it is very hard to contain such fast moving particles. If the plasma "escapes" the confinement and contacts anything (ie. the walls of the Tokamak) it rapidly cools down to temperatures below where fusion can happen.

The immense engineering challenge here is to heat plasma to ridiculous temperatures, and keep it confined in a very small volume at great temperature and pressure to mimic conditions that give rise to nuclear fusion in the center of stars.

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