I first heard about the Tokamak in highschool 10 years ago and was wondering how far the technology has come since then. Can it sustain a reaction for more than a few seconds? Are these devices still huge or have they been made on a smaller scale?
Yes, at JET. Lifetime of the plasma: 20–60 s
At ITER: It will operate over a wide range of ITER plasma scenarios, from short plasma pulses (a few hundred seconds) with enlarged fusion power (700 MW) to long plasma pulses of 3,000 s
They have to be large in order to give out more energy than they consume. This is the ITER link, the one planned and already being built, to get the size idea.