Helion Energy is building Tiny Merge, a fusion device that is one-eighth the size of its seventh generation prototype and will serve as a testbed for faster iterations of its designs. (Helion Photo) EVERETT, Wash. — With just three years left on a hard deadline to prove its fusion approach works, Helion Energy is still wrestling with fundamental questions — and it’s building a new, smaller machine to help find answers faster. Since launching mor…