Much the same method as yours.. A geometry-bevelled curve for the glass, with a *Solidify* modifier to make it a tube. A duplicate of the curve, with a smaller bevel, for the gas. 

The glass is just a standard, colourless,  almost 0-Roughness, almost 1-Transmission principled BSDF.

The gas uses a the 'Facing' output of a *Layer Weight* node to make the mask shown on the left, below,  to mix between a *Transparent* and *Emission* shaders as shown on the right.

[![enter image description here][1]][1]

..but it still takes a fair bit of tweaking to make it feel 'gaseous'..

[![enter image description here][2]][2]


  [1]: https://i.sstatic.net/4i559.png
  [2]: https://i.sstatic.net/85JLa.jpg