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Capacitively coupled Plücker tube: dry air This series shows the capacitively coupled Plücker tube presented [url=https://trad-lighting.net/gallery/displayimage.php?pid=1284]there[/url] operating at 5-15 kV and ~30 kHz in dry air at a pressure ranging from about 10 mbar (top) to less than 1 mbar (bottom). The color aspect of the discharge is very different from that observed with the electroded tube shown [url=https://trad-lighting.net/gallery/displayimage.php?pid=1137]there[/url] because in the latter case more current could be coupled to the discharge and reactions at the metal electrodes caused a faster cleanup of oxygen, which resulted in the gas composition being more nitrogen-rich than in the present case. Keywords: Lamps

Capacitively coupled Plücker tube: dry air


This series shows the capacitively coupled Plücker tube presented there operating at 5-15 kV and ~30 kHz in dry air at a pressure ranging from about 10 mbar (top) to less than 1 mbar (bottom). The color aspect of the discharge is very different from that observed with the electroded tube shown there because in the latter case more current could be coupled to the discharge and reactions at the metal electrodes caused a faster cleanup of oxygen, which resulted in the gas composition being more nitrogen-rich than in the present case.
DSCF0197m.jpg CC_Air_m.jpg CC_Water_m.jpg Philips_126564.jpg DSCF0291m.jpg
Lamp/Fixture Information
Manufacturer:Me
Lamp
Lamp Type:Dry air low pressure (capacitively coupled)
Filament/Radiator Type:Nonthermal discharge in low-pressure dry air
File information
Filename:CC_Air_m.jpg
Album name:Max / Misc lamps and lighting
Keywords:Lamps
Filesize:1838 KiB
Date added:27 May 2026
Dimensions:1500 x 2293 pixels
Displayed:254 times
DateTime Original:2026:03:14 19:33:35
Exposure Time:1/25 sec
FNumber:f/4
File Source:Digital Still Camera
Flash:No Flash
Focal length:22.3 mm
ISO:160
Model:X-E4
Software:Adobe Photoshop 25.7 (Windows)
White Balance:0
URL:https://trad-lighting.net/gallery/displayimage.php?pid=1283
Favourites:Add to Favourites

Comment 1 to 2 of 2
Page: 1

Drew   [Wed 27 May 2026 at 16:34]
Very nice, interesting to see how the color seems to get more saturated near the middle and then get a little more grey at the bottom. Typically the only time I see that more grey color is when oil starts backstreaming from my pump in the range of 5 mbar which is around the lowest I can really get with my pathetic setup. Beautiful demonstration
Max   [Thu 28 May 2026 at 08:41]
Thanks Drew. Good point about the possible oil contamination, I need to do some spectroscopic analysis to check for CN bands and to verify the exact nature of the plasma at the lowest pressure level. My pump is new (got it this Christmas) and reaches a minimum pressure of 0.05 mbar (measured with a baratron and a Pirani gauge in dry air). Also, the lamp was connected to the setup via a relatively long and narrow tube, so if there was indeed an oil pollution, I don't think it was significant.

Comment 1 to 2 of 2
Page: 1