2009 Volume 93 Issue 8A Pages 514-520
A low-pressure mercury (Hg) cold cathode lamp (CCL) was filled with neon at a few kilopascals and mercury (Hg). It was important to grasp the difference in electrode characteristics between normal lighting condition (Hg-vapor exists in the CCL) and end-of-life lighting condition (Hg-vapor is used up in the CCL) when we developed the CCL electrode. Then we investigated the variation of the electrode characteristics in some electrode materials with the CCL (Hg plus) filled with Hg and neon (Ne) and the CCL (Hg less) filled with only Ne. It is clear that when the CCL was filled with Hg, the cathode fall voltage (CFV) was higher and the negative glow of the CCL (Hg plus) spread larger (the current density on the electrode was lower). The former result is due to the fact that the value of γ (Hg2+) was lower than that of γ (Ne+), and the later result is due to the fact that the Hg ion's mobility was higher than the Ne ion's one. By observing the CFV waveform, it is clear that the CCL (Hg less) was in abnormal glow discharge, whereas the CCL (Hg plus) was in normal glow discharge. According to these results, the electrode consumption increased rapidly when the Hg was used up in the CCL.