If a laser is continuously emitting light, then there must be power to replenish that lost energy in such a way that the laser action can continue. The power must maintain the necessary population inversion to keep the laser process going, and that implies a pumping mechanism to elevate electrons to that metastable state . The use of helium to "pump" electrons into a metastable state of neon in the helium-neon laser is an example of such a mechanism.