A xenon-filled discharge tube glowing light blue — Spectrum = gas discharge tube: the noble gas: xenon Xe. Used with 1,8kV, 18mA, 35kHz. ≈8" length.
Photo Credit: By Alchemist-hp (talk) (www.pse-mendelejew.de) - Own work, FAL, https://commons.wikimedia.org/w/index.php?curid=9598160