How do Tokamaks work?

Ive been reading into the nuclear physics behind devices like tokamaks which are promising candidates for a viable fusion reactor. The thing is, from everything I've seen and read it looks like the popular model for a tokamak is only the in between stage. Its like describing the forces on an airplane in flight but neglecting to explain how it takes off or lands. Can anybody tell me how they get those things fired up and cooled down? And I dont mean the ignition process or simply turning off the input power. I mean how to get the gas inside the darn thing to stay in the containment field until its been ionized? or is it ionized already? Anything at all would be much appreciated. =]