My understanding of this was that basically we have achieved the scientific break even point already. That is we can have short lived fusion in a tokamak where

My understanding of this was that basically we have achieved the scientific break even point already. That is we can have short lived fusion in a tokamak where we produce more energy than is consumed by the reaction. The trick is getting to practical break even: you also need to power the magnetic field. It seems that we are getting closer with every attempt to getting to that break even, but it is very slow progress. I also remember reading something about an attempt at building a tokamak that didn't run continuously, but in short bursts. The idea was that it was more feasible to actually get closer to the break even that way. Anyone have a quote in what our current best efficiency is?