Discharge tubes with krypton, krypton+iodine, and xenon
Channel: Carl Willis
Date: 2013-01-29

Three glass tubes, each 24 inches long and 1.5 inches in diameter, are exhausted to high vacuum and backfilled with gases.  The tube at the top contains pure krypton at 200 torr; the tube in the middle contains krypton at 100 torr plus a crystal of iodine (vapor pressure ~0.3 torr); and the tube at the bottom contains pure xenon at about 30 torr.  Gases are delivered at UHP purity through a metal-sealed system and pressure is measured with a 1000-torr Baratron manometer.  The different colors and structures of the discharges are discussed as they relate to fill gas composition--particularly the improvement caused by the addition of iodine to krypton.  As always, feedback is welcomed.  Thanks for watching!