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Neon discharges at different pressures Shown here are two experimental low-pressure neon discharge tubes (T4) used for plasma studies. The lamps were made using components taken from standard compact fluorescent lamp production. Here the lamp runs at around 0.17 A on an HF 13 W fluorescent tube driver. The lamp at the top is filled at 4.0 mbar and presents a slightly more orangish light color than the bottom one, which is filled at 13.3 mbar. This subtle difference in color is due to the higher electron energy in the discharge of the top lamp, which results in more orange, yellow and green spectral lines being emitted. Both lamps have a striated plasma pattern which is the result of a modulation of the electron energy in the discharge, causing a cycling excitation of the gas fill. That pattern is more pronounced at low pressure due to a lesser spread in energy of the electron gas as a result of the reduced collision rate with atoms in the lamp's tenuous atmosphere. Keywords: Lamps

Neon discharges at different pressures


Shown here are two experimental low-pressure neon discharge tubes (T4) used for plasma studies. The lamps were made using components taken from standard compact fluorescent lamp production. Here the lamp runs at around 0.17 A on an HF 13 W fluorescent tube driver. The lamp at the top is filled at 4.0 mbar and presents a slightly more orangish light color than the bottom one, which is filled at 13.3 mbar. This subtle difference in color is due to the higher electron energy in the discharge of the top lamp, which results in more orange, yellow and green spectral lines being emitted. Both lamps have a striated plasma pattern which is the result of a modulation of the electron energy in the discharge, causing a cycling excitation of the gas fill. That pattern is more pronounced at low pressure due to a lesser spread in energy of the electron gas as a result of the reduced collision rate with atoms in the lamp's tenuous atmosphere.
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Lamp/Fixture Information
Manufacturer:Philips
Model Reference:#2-36/6 (top) and #2-36/11 (bottom)
Lamp
Lamp Type:Neon low pressure (4.0 mbar top, 13.3 mbar bottom)
Filament/Radiator Type:Nonthermal discharge in neon
Base:Flying leads
Shape/Finish:Tubular clear
Burning Position:Universal
Physical/Production
Factory Location:Eindhoven, the Netherlands
Fabrication Date:2003
Application/Use:Plasma studies
File information
Filename:DSCF4826m.JPG
Album name:Max / Misc lamps and lighting
Keywords:Lamps
Filesize:721 KiB
Date added:May 26, 2025
Dimensions:1500 x 1000 pixels
Displayed:16 times
DateTime Original:2025:05:26 22:46:24
URL:https://trad-lighting.net/gallery/displayimage.php?pid=865
Favorites:Add to Favorites

Comment 1 to 7 of 7
Page: 1

Ria   [May 26, 2025 at 10:25 PM]
Oh now this is something special Cool
Sammi   [May 26, 2025 at 10:27 PM]
Outstanding as always.! Mind Blown Love
AgentHalogen_87   [May 27, 2025 at 04:10 PM]
That's a nifty idea. Short neon tubes in 4/6/8W length mini battens to make our own shapes and letters Wonder
Max   [May 27, 2025 at 04:35 PM]
Interestingly, some lighting manufacturers offered special discharge lamps to that end, either as negative-glow lamps with shaped electrodes, or as high-voltage sign tubes. By the 1950-60s all of them had quit that market segment, now catered for entirely by the neon sign industry which has a more suitable manufacturing approach. However, a key advantage of the present hot-cathode discharge tubes, beside their low operating voltage, is certainly a higher lumen efficacy for smaller lamps due to the significantly reduced electrode losses.
Tuopeek   [May 27, 2025 at 06:41 PM]
Is this pure neon running on fluorescent ballasting? I would have thought it would need to be Penning even with a hot cathode to start.
Max   [May 27, 2025 at 07:46 PM]
It is pure neon indeed as the application of this tube is the study of plasma processes relative to neon only. The electrodes are pre-heated here, so thermionically emitted electrons ensure a successful ignition even though there are no Penning reactions in the lamp's atmosphere. I have not measured the driver's exact OCV, but it must certainly be near the kV level as I manage to ignite xenon-filled lamps which have a much higher starting voltage requirement than these (pure) neon tubes. It's even worse when there are molecular impurities present in the gas fill, such as shown there, but ignition is not a problem with the 13 W HF driver used here. That goes to show that a Penning mixture is not a hard requirement if enough voltage is applied to the lamp, which is clearly the case here. Penning becomes useful if one wants to minimize the lamp's starting voltage in a given circuit/system, which is not needed here.
Tuopeek   [May 27, 2025 at 08:59 PM]
That's interesting Max, would love to have a go at making something along this line if my glass skills and available parts are up to it. Very Happy

Comment 1 to 7 of 7
Page: 1