Fusor Forums

I bought a copy of an Australian/UK magazine "New Scientist" dated 14th of July. On page four they mention that the DIII-D Tokamak has been able to spin a plasma successfully for long periods of time by correcting tiny imperfections in the magnetic containment field with feedback loop corrected magnets. The upshot of that was it allowed Ronald Stambaugh (US National Fusion Facility) to double the plasma pressure and quadruple the fusion rates previously achieved.
I had a bit of a surf on the net and found an abstract of one of his papers: "Higher fusion power gain with current and pressure profile control in strongly shaped DIII-D tokamak plasmas". It mentions they have a an input to output power Q of 0.0015 which sounds pretty good to me!. It sounds like pretty interesting reading but I can only get hold of the abstract and not the actual paper.

Define "long periods of time." What are they up to now, 10, maybe 20 milliseconds?

--PS

That initial article gives no real facts or figures apart from the mention of quadrupling fusions rates. I found the Q figure in one of their abstracts on this website:http://fusion.gat.com/diii-d/. I also did a bit more looking around the website and found this PDF document: http://fusion.gat.com/pubs-ext/miscpubs/A23345.pdf which though dated 1999 mentions on page 12 that their longest stable run was 2 seconds, their accompanying graphs show 4 seconds on the x axis, but that their 5 new gyrotrons (whatever they are) will give 10 second pulses. So unless I've really badly read the documents wrong and they are referring to something different altogether, I'd say the "Long periods of time" would be relative to 2 seconds stable plasma time. I guess it would be easier if I just emailed em and asked : )

regards
Mark

Hmmmm. I wonder if a diffirent version of a TV "YOKE" could be used to achieve the "spin" ?

Those guys had a very sophisticated feedback system that had to allow for even the Earth's magnetic field to succeed. The real challenge was to get such an actively corrected, uniform field for the spin to take place in.