I was wondering if we could create some gaseous matter whose ionization energy is very low, so it can be fully ionized under room temperature, thus converted in plasma. I know that plasma loses energy quickly by radiation, if we could harness this radiated energy, won't this violate the second law of thermodynamics? I then thought that the radiated energy may be re-absorbed by other non ionized atoms, but if the ionization energy was law enough, the number of ionized matter would be much more than non ionized, and so it can keep radiating at room temperature. I don't know how thermal equilibrium is achieved here. Assuming the existence of such a kind of matter is far from true, but I want to know what exactly defends the second law in that case?