The Hydrogen Preheater is a tile entity of the multi-block structure Preheater Housing. It is the center block of the structure that heats up hydrogen into plasma.
To function, the block needs deuterium, tritium, heat of at least 150 million degrees Celcius, and the multi-block structure surrounding it. Deuterium and tritium is supplied on its sides, while a part of the structure focuses a Heat Ray onto another side. The plasma output is the top of the block.