There’s something unsettling about a particle beam illuminating a darkened room with purple fluorescence.
In this video, YouTuber clagwell demonstrates his own variation on the Lenard tube, with amazing results. Perhaps it’s the music, or the tube’s strange design, or the fact that the beam in question emits X-rays. But the video, with the electron gun seen in action at 1:43, is somewhat haunting.
“Quite honestly, I am done playing with this one. The X-Ray hazards are too much. At one point I measured output in the rads as opposed to millirads.” – clagwell
Originally created by Philipp Lenard, a Lenard tube is itself a variation of the Crookes tube. This device, developed by William Crookes, is a form of cold cathode tube that consists of a sealed glass tube and two electrodes at either end. When electric current is applied, electrons (or cathode rays) are projected, causing a fluorescent glow within the tube (thank you, Wikipedia).
Lenard devised a “window” on a Crookes tube (above) to see if these cathode rays would exit the tube into the atmosphere. He would eventually be awarded a Nobel Prize in 1905 for his discoveries involving the “Lenard window.”
You can find more information on Lenard rays over at Lateral Science.