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Pulsed xenon lamp at low current Pulsed xenon lamps differ mainly from flash tubes in the way they are driven. Instead of discharging a capacitor into single intense flashes, the arc in those lamps operates in the burst regime at typically twice the AC mains frequency (i.e., 100 pulses per second on 50-Hz mains), fed by a transformer-capacitor circuit. The present Philips model 126564 was made in the 1970s and is designed for an average power dissipation of 100 W at 450–630 V. Here I run it at high voltage (several kV) and low current (25–30 mA), which results in a filamentary plasma which does not fill the whole discharge tube volume. Interestingly there is a greenish glow that surrounds the plasma channel, which is caused by oxygen impurity in the xenon fill. Keywords: Lamps

Pulsed xenon lamp at low current


Pulsed xenon lamps differ mainly from flash tubes in the way they are driven. Instead of discharging a capacitor into single intense flashes, the arc in those lamps operates in the burst regime at typically twice the AC mains frequency (i.e., 100 pulses per second on 50-Hz mains), fed by a transformer-capacitor circuit. The present Philips model 126564 was made in the 1970s and is designed for an average power dissipation of 100 W at 450–630 V. Here I run it at high voltage (several kV) and low current (25–30 mA), which results in a filamentary plasma which does not fill the whole discharge tube volume. Interestingly there is a greenish glow that surrounds the plasma channel, which is caused by oxygen impurity in the xenon fill.
Screenshot_2026-05-02_194726.png 1000036650.jpg Philips_126564.jpg WL-H33GL-T400-DX-N2-1.jpg WL-H33GL-400-R-76.jpg
Lamp/Fixture Information
Manufacturer:Philips
Model Reference:126564
Lamp
Lamp Type:Xenon pulsed
Electrical
Wattage:100 W (average, at nominal regime)
Physical/Production
Factory Location:Eindhoven, the Netherlands
Fabrication Date:1970s
Application/Use:Signaling
File information
Filename:Philips_126564.jpg
Album name:Max / Misc lamps and lighting
Keywords:Lamps
Filesize:820 KiB
Date added:02 May 2026
Dimensions:1500 x 1500 pixels
Displayed:14 times
DateTime Original:2004:06:01 22:17:12
Exposure Time:1/80 sec
FNumber:f/5.6
Flash:No Flash
Focal length:55 mm
ISO:400
Model:Canon EOS 350D DIGITAL
Software:Adobe Photoshop 25.7 (Windows)
White Balance:0
URL:https://trad-lighting.net/gallery/displayimage.php?pid=1239
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Comment 1 to 4 of 4
Page: 1

Drew   [Sat 02 May 2026 at 12:54]
That looks so cool! Green is such a rare color to see in ~room temperature discharges. I thought an impurity of nitrogen is what caused a green glow in xenon, but I don't remember exactly I just know it was one of the two main ingredients of air. I might try and do this with one of my tubes and see how it looks, of course with UV shielding since it's quartz.

What would the application be for one of these rapidly pulsed lamps? I would assume at 100Hz the flashing is barely perceivable.
AgentHalogen_87   [Sat 02 May 2026 at 21:04]
Awesome effect! Are those green ghosts in the tube from deliberate oxygen in there or a slight leak / error during manufacture?

@Drew I think they get used for pulsing aircraft obstruction beacons on tall buildings.
Sammi   [Sat 02 May 2026 at 23:43]
Another wonderful picture.! Love
Max   [Mon 04 May 2026 at 08:04]
Thank you Sammi! I was really puzzled when I first saw that green glow around the xenon plasma filament, I've never seen that in any other xenon flash/pulsed lamps.

AgentHalogen_87 - I don't think oxygen was introduced deliberately, and there certainly is no leak (even a tiny one) or the lamp would be full of air by now. It is more likely that this is caused by an improper lamp processing during production, resulting in an unclean gas fill or component (electrode or wall).

Drew - Green is not a common discharge color indeed and nitrogen never causes that, its emission is either blue or red depending on the electron energy. This particular lamp finds an application in signaling. Its burst-pulsed operation makes it more visible/noticeable than single-flash signals.

Comment 1 to 4 of 4
Page: 1