Hello there physicists! I am here to ask a few straightforward questions regarding nuclear fusion accomplished here on Earth. Question 1: How does a magnetic field contain the heat produced by nuclear fusion in the reactor? If we look at the example of Deuterium fusing with Tritium, a high energy nuerton is release with an ample amount of energy. I assume this energy is automatically transferred to heat. In order for the heat to be contained (and not incinerate absolutely everything that surrounds it), it would have to energize ions. Am I correct in saying that the heat is contained through fast moving ions that are held back with the magnetic field? If I am, then, what happens to the neutrons?(Yes, I know it was a series of questions). Question 2: Why is the fusion process not sustainable on it's own? What I mean here is, if we were to simply bring the temperature high enough to start the fusion process, why then, could it not sustain itself and continue indefinitely so long as we supply the fuel (just like the Sun)? This arises from the fact that the current process of fusion established in the Tokamak produces less energy than the energy required to keep the fusion process going. Question 3: Why is cold fusion considered "impractical?" Thank you very much to all those who answer these questions. I greatly appreciate it!