Great idea.
I would think that living inside a sphere of water would work just as well.
Failing that, just emulate the earth. A giant magnetosphere with lots of atmosphere ;).
Well, at least the scientists are now considering cosmic rays. For a while there, it seemed they thought Columbus was about to sail across the Atlantic. What does it take to generate plasma? High heat and energy, no?
A huge manmade magnetic field should also protect from radiation. But won't a large magnetic field and producing plasma use up a lot of energy?