# The problem of TOKAMAK

1. Feb 8, 2006

### chaoszen

I recently read from newspapers that china has built a experimental advanced superconductive TOKAMAK , and such an experiment is going to set about. It also mentioned if the experiment exceeded, China would be the first country on the planet owing such a experimental equipment.I just roughly translate the article to english, of course the article didn't mention the detail of this apparatus which costs "only" 40 million US dollars.
As a skeptic,I really doubt how advanced this experiment is.It seems that it's designed basing upon the principle of controlled nuclear fusion of TOKAMAK, which had been the focus of fusion research quite long ago.
so here I eagerly yearn to know what's the problem encountered by researchers when applying TOKAMAK equipment to trigger fusion reaction.AND is there a road through these barriers?

2. Feb 8, 2006

### alfredblase

good question...

3. Feb 10, 2006

### Staff: Mentor

The Tokamak (Toroidal Chamber) concept has been the main approach with respect to magnetic confinement systems, as opposed to inertial confinement.

The major problem has been one of heating the plasma to high enough temperatures to initiate and sustain the fusion reaction, while confining the plasma for sufficient time to allow more energy to be produced from the fusion reaction than is put into heating the plasma. The magnetic fields must be strong enough to contain the plasma in a stable configuration, and the pressure imposed by the magnetic field is proportional to B2.

Then there are other technical issues related to materials integrity and power conversion.

I doubt that the Chinese were able to manufacture a reasonable Tokamak for $40 million. 4. Feb 16, 2006 ### ludi_srbin 5. Feb 16, 2006 ### Pengwuino I thought Japan had Tokamak reactors for a while now.. 6. Feb 17, 2006 ### theCandyman They have, but it is not just them that have them. I think Russia has a few as well. Also, the page ludi_srbin linked should have information on Europe Tokamaks [JET - Joint European Torus]. 7. Feb 17, 2006 ### Astronuc ### Staff: Mentor 8. Feb 21, 2006 ### Geoff St. Germaine I read this article a while ago and we have a professor here who has some ties to this reactor. The$40 million is for an upgrade to the HT-7 tokamak, not for a new machine. The article was quite misleading about this. IIRC, the upgrade is to install superconducting poloidal field coils. HT-7 is a medium-sized limiter machine with a major radius of 1.22 m and a minor radius of 27 cm. I doubt that this machine will be performing any D-T fusion. It is been upgraded several times, and was originally in Russia under the name T-7.

9. Feb 21, 2006

### Geoff St. Germaine

I wonder what that was filmed with. I know that NSTX has a camera that was built by the Princeton Scientific Instruments that can record at 1 million frames per second.

Here are some more videos from NSTX. These aren't with the "super camera", but are with another one of their other fast cameras that can record 1000 frames per second.

Last edited: Feb 21, 2006
10. Feb 21, 2006

### chaoszen

11. Feb 21, 2006

### Geoff St. Germaine

AFAIK, JT-60U has the has the record for the highest fusion triple product, the record for the highest central ion temperature and the record for the largest equivalent Q (1.25). The other machine close to JT-60U is JET, both of which are considerably larger than HT-7.