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Registered Member #95
Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308
I built my first tesla coil a few days ago, its just a cute 8 cm tall SGTC. Finally having some streamers to experiment with, I tried the lightbulb plasma globe trick with great success.
However with a different light bulb I found in a microwave oven I get no plasma at all. The filament warms up a bit, and small streamers shoot off the outside of the bulb, but otherwise its completely dead. So I think there must be a hard vacuum in the bulb, otherwise I should see some streamers, right? So could this bulb be used for small amounts of x-ray production? This guy seemed to make it work with a vacuum tube with a foil cap.
Registered Member #180
Joined: Thu Feb 16 2006, 02:12AM
Location: Ontario, Canada
Posts: 187
Does anyone know why the filament would heat up like that? There are no streamers comming off of it to cause the heating, so there must be something else heating it... possibly some x-rays, but I have no idea.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
The fact that filament is glowing is very interesting..could it be from electron bombardment?
But from other side, it's a bit chiken and egg thing. Once filament is hot, the bulb will act as a diode, rectify the current and nullify the capacitive coupling effect through glass.
You would need some kind of another electrode to act as a plate for it.
Registered Member #540
Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969
If it is acting as a diode you may be exceding its max plate voltage rating and producing X-rays or the filiment might not be hot enough to emmit that many electrons so it is like a plasma globe. Ethier way you are producing X-rays.
Registered Member #95
Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308
Cool, I'll take spesial care of this light bulb then for later experiments.
Does anyone know for sure what causes the filament to heat? Electron bombardment was the first thing I thought of too. I assume the currents from my Tesla coil are too low to heat the filament, after all the HV power supply for the coil is a mere flyback run form 12 volts and a simple 555 driver. Also none of the other bulbs get filament heating.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
As a continuation of Vasil's point, you might be able to get an X-ray badge to detect the Xray level. If you are indeed suspicious of Xrays you should take care to protect yourself and stand at least 6 to 9 feet from the source and shield yourself. Prolonged Xray exposure is not benign.
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X-ray tube from a light bulb?
Also none of the other bulbs get filament heating.
