The basic problem of nuclear fusion is that it occurs at incredibly high temperatures. The plasma at the heart of a reactor in which the process takes place can reach 150 million degrees Celsius. That kind of heat needs a strong force to control it, something on the order of a magnetic field 13 of teslas in strength. Basically, the forces and stresses inside a fusion reactor are crazy-strong and they tend to wear out any equipment that they come into contact with pretty dang quick. That's where the new breakthrough comes into play: weaving.