Answer:
Plasma can be artificially generated by heating a neutral gas or subjecting it to a strong electromagnetic field to the point where an ionized gaseous substance becomes increasingly electrically conductive.
Well I can't see the following physical properties you talked about in the question.
Mass per unit volume ratio is called density.
Bad, it's bring more hatred to the world
Unless the ring by design will have restriction for any outward expansion. The hole will get larger / bigger as you heat this up. The more you heat an object the more it expands, thus the larger the hole gets. The only case is when outward expansion is restricted, the expansion will be inward as it is the only direction the ring can expand to.
