Here is the gas discharge tube.

这里是个气体放电管。

He was doing experiments in a gas discharge tube.

实验是在一个气体放电管中进行的。

And what is inside the gas discharge tube is gas at low pressure.

气体放电管里，有处于低压下的气体。

Shell pumps up liquid outlet 8 connected with the discharge tube 9.

泵壳上的液体排出口8与排出管9连接。

And so if he gets the voltage high enough, this gas discharge tube will glow.

如果管中的电压足够高的话，气体放电管将会发光燃烧。