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Chinese Tokamak reaches over 100M degrees

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Re: Chinese Tokamak reaches over 100M degrees

#141

Post by mcv »

antx wrote: post #122
mcv wrote: post #106

Earlier quoted context omitted.

It's also wrong. Kelvin is not in degrees. It's just 100M Kelvin.

You're right, the degree was removed in 1967, because Kelvin's units are considered absolute. However, one could argue that, since it has a scale, each "step" or "unit" can be considered a "degree", like in a literal scale. In informal conversation, we should not be so pedantic. Even some modern scientific textbooks still include the degree.

> the degree was removed in 1967

I did not know that. I've always thought it was originally defined as units Kelvin, without degree.

Re: Chinese Tokamak reaches over 100M degrees

#142

Post by grogenaut »

hkt wrote: post #134
marcosdumay wrote: post #98

Earlier quoted context omitted.

Well, there is almost certainly somebody that read the number and thought about Fahrenheit.

Do scientists use farenheit? Genuine question

When they look at a weather report in the US. Otherwise no.

Re: Chinese Tokamak reaches over 100M degrees

#143

Post by snarfy »

mrpdaemon wrote: post #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…

Yep even if it's hot enough it still needs the correct densities. It's akin to trying to compress a balloon with your hands. If enough 'hands' all push simultaneously it can work, but you can imagine the instabilities.

Re: Chinese Tokamak reaches over 100M degrees

#144

Post by ajmurmann »

fyfy18 wrote: post #114
zaarn wrote: post #107

Earlier quoted context omitted.

Fusion is notoriously underfunded. More money means you can buy better gear, hire more workers, complete projects faster and run multiple parallel sites to complete various goals at the same time. Of course there is some point where adding more funding will not advance the speed as much anymore but I doubt were even close to that point at the moment.

Why is it so underfunded? The first country to build one will be taking a big step to reducing their dependence on other countries for energy. I can understand big oil exporters not wanting to push it too much (although it's unlikely to come into fruition for the current generation of politians), but for others isn't it a no brainer?

Another (completely stupid) reason is that it's "nuclear" energy. The general public has a hard time understanding that fusion and fission have very different risk profiles. I recall that after Fukushima some countries cut their budget for fusion research because nuclear energy is clearly bad and unpopular.

Re: Chinese Tokamak reaches over 100M degrees

#145

Post by stevespang »

gravitational compression on the level of what occurs in the stars cannot be achieved on earth - - therefore, net positive fusion will never occur. Why not invest all that money in solar, wind and wave energy instead ? Anything radioactive at large scale seems to always be aligned with government / military industrial complexes.

Re: Chinese Tokamak reaches over 100M degrees

#146

Post by bagacrap »

maaaats wrote: post #95
i_am_proteus wrote: post #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 th…

> "100M degrees" (Kelvin) Off topic, but this distinction made me laugh. Like the difference between Kelvin and Celsius would throw everything off.

Shouldn't it just be 100 K, i.e. no "degrees"?

Re: Chinese Tokamak reaches over 100M degrees

#147

Post by phkahler »

i_am_proteus wrote: post #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 th…

Didn't old-school CRT televisions "heat" electrons to more than 10KeV?

Re: Chinese Tokamak reaches over 100M degrees

#148

Post by ravar »

muhbags wrote: post #136
hkt wrote: post #134

Earlier quoted context omitted.

Do scientists use farenheit? Genuine question

Never. It's either no units (theoretical physics), eV (particle physics) or Kelvin/Celsius for experimental physics.

Technically there is Rankine if you want to do thermo in imperial units.

Re: Chinese Tokamak reaches over 100M degrees

#150

Post by randlet »

phkahler wrote: post #147
i_am_proteus wrote: post #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 th…

Didn't old-school CRT televisions "heat" electrons to more than 10KeV?

I don't know about CRT's but 10KeV is not particularly energetic. A CT unit may operate in the ~100-200kV range (so max energy of 200keV) while radiation therapy units operate in 6MV-18MV range (so electron accelerated up to 18x10^6 eV).

I don't know much about fusion, but my guess is the 10keV is impressive because it is a self-sustaining fusion reaction rather than being impressive because of the absolute energy of the reaction?

edit: someone down the page mentioned that containment is the issue. In a CRT you are just accelerating an electron across a few thousand volt potential and slamming it into the screen.

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