E8R06986 - Spectrum Tube - Helium | Findel International
Tubes with inert gases excited with high voltage. From left to right: Helium, Neon, Argon, Krypton and Xenon. Each tube emits a different color and in Stock Photo - Alamy
Inert gas tube hi-res stock photography and images - Alamy
Solved Helium (He) Gas discharge tube: Bright line emission | Chegg.com