If you want to make new helium, it's far easier to go the other way.

You just need quite a bit of Polonium, Thorium or Radon. Put it in a pool - and then wait a while. You just gotta collect what bubbles to the surface.

Yeah, but it gets quite warm

If you come up with a process to do that efficiently, the helium will be a lovely bonus but not remotely the most important result. :D

Nuclear fusion?