And we have to find the He-3. Not quite as abundant as H-2, is it?
He-3 is rarer than hen's teeth! He itself is not that abundant, but He-3 constitutes only 0.00013% of all He.
H, of course is very abundant and H2, though rare, amounts to 0.015% of all H. That makes its relative isotopic fraction 3 orders of magnitude greater than He-3.
Above info is from my old (40+ years) chart of the nuclides, but I doubt the data have changed significantly.
Now I'm assuming here that the sun's fusion reactions produce mostly He-4. Is there some reason why we can't, or it that just way beyond our capabilities here on earth?
I have He-3 in my watch. :-)