GEC 60W SLI/H 2

An interesting phenomenon arises during the early stage of the lamp's run up phase. As sodium vaporizes, nearly all alkali atoms entering the energetic noble-gas discharge get ionized by the fast electrons there, resulting in a cloud of positive sodium ions. These ions are then pulled back towards the negatively charged wall, where they recombined, thus forming a layer of sodium vapor which is excited by the edge of the diffuse plasma. This mechanism of ionic pumping results in the characteristic sodium-yellow blanket that covers the burner walls as the lamp warms up. Although this ion transfer mechanism remains operational during full regime, to the extent that it even impacts the lamp's performances, its visual effects are not as dramatic as during the warm up phase due to the lowering of the plasma's electron energy (which reduces the ion flux to the wall), and the homogenization of the discharge color due to the presence of sodium in large quantity overall, dominating the radiative processes of the plasma.