He had a tube with electrodes potted in it filled with atomic hydrogen. And by applying a voltage, he was able to get the gas to glow.

那是个装满了氢原子并含有电极的管子,通过增加一个电压，他让气体燃烧起来了。

麻省理工公开课 - 固态化学导论课程节选

This is the diagram taken right from your text, there are the two electrodes coming in and this is atomic hydrogen in the gas tube.

这是从教科书上复制下来的图表，这里有两个电极进来,这是气体管中的氢原子。

麻省理工公开课 - 固态化学导论课程节选