burning nuclear plasma

Etymology
From being self-sufficient in the production of the amount of heat necessary to continue the nuclear processes, hence "burning" (where in a chemical fire, the reaction processes produces enough heat to continue reacting in the heat portion of the fire triangle); and being a plasma (a highly ionized gas) where nuclear processes occur.

Noun

 * 1)  A plasma undergoing nuclear fusion where the amount of fusion reactions is sufficient to produce enough energy to maintain the temperature of the plasma at a level necessary for further fusion processes.