Mining for Helium 3 on the Moon

[najab]

><i>Dude, I just told you. As far as we are concerned it is infinity.</i><p>No, I asked you - what is the Q-factor of the Z-machine? Not potentially, not some day - today.</p>

 

[najab]

I'm trying to remember which European reactor it is that achieved Q=1 a couple years ago - I'm 90% sure it was JET, but can't find a link to a source at the moment.

 

[grooble]

What is all this Q stuff, which is the best?

 

[tap_sa]

Call me when the Q factor is ~20.

 

[henryhallam]

Yep it was JET. But only for a short period of time, less than a second I think, due to magnet overheating & fuel exhaustion.

 

[henryhallam]

A second or so of sustained Q>1 fusion at JET is a lot closer to a useable power plant than a few microseconds at Sandia. JET has done a magnificent job and paved the way for ITER to demonstrate sustained output at a power level where you could start to recover some energy, over a long period of time.

 

[avmich]

AFAIK, JT-60U from Japan achieved Q=1,25 (i.e., it produced 25% more energy than it spent) in 2000. Z machine did have a neutron emission (Russians did that in 1991 on Angara-5 reactor, making a long-standing record for neutron emission per pulse), but no actual thermonuclear detonation, thus no microexplosion.<br /><br />But to have a net economic gain, you have to have Q about 10. All current reactors are below it.