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Author Topic: what is that?  (Read 598 times)
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I saw this crazy effect when driving a near vacuum bottle with a laptop fluorescent driver, I know it musy be from the high frequency of the HV ac, but what is that exactly called?


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And to be more exact im talking about the apparent standing waves you have to look close, the camer only just picks them up
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Light reflections inside the tube???
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I don't think so, it has a bit of a wave to it, it would be perfectly straight I would think if it was a refelction
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Plasma maybe? Nice violet color?
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Werird part is up to 11 waves all evenly spaced apart are visible but only at a certain pressure, not too low or too high, mostly low pressure
the part that baffles me is that I haven't measured it but I can't imagine the frequency to be more than a few hundred khz max, if that was the form of a sine wave that frequency would be really high since its spaced so close,
perhaps at a certainpressure that's a harmonic of some sort?
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A local museum just opened up an exhibit (http://www.crmi.org/exhibits/self-illuminated/) by Wayne Strattman who seems to the world expert in neon and plasma displays.  I don't know if his two books (Neon Techniques and Neon:The Next Generation) would answer your question, or possibly contacting Wayne.
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It looks like a low energy plasma discharge in a predominately nitrogen gas mix under low pressure... Or that's what the one I made when I was in my early teens with the output of a 2 foot tall tesla coil.

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I can't imagine it being anything special, just a partially vacummed glass container, I don't think my refrigerant vacuum pump goes too low, and its a fluorescent bulb driver from a laptop, don't think it can hit more than 1kv
just strikes me as weird how the spacing is like mm apart which would be in the Ghz range which I sure know its not(looked it up it says typ. 60khz)
I may contact that guy im sure he's seen it and can tell me what it is,
it must be plasma for sure, if you remember your expirement back then did you see those waves too?
its definetly driving the driver harder than usual, after a few minutes it shuts down, can't wait until I finish my HV supply ill be able to control the voltage alot more to see if I can't recreate it with another driver,
as for pressure regulation, anyone know an easy way to control/meaure that?
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You don't need a great deal of power to do that especially at a few inches of vacuum, something that most any refrigerator coolant pump can do. Mine did, I used 25KV Neon sign transformers and balloons to carry the Gas home that I used to get from the neon sign company. When I fired up my "Coil" all the neighbors visited my house... Had eventually to make a hiding place under the house. I made a rotary spark gap transmitter once... Never built a receiver though, this was when I was 14 and 15 years old... I left home at 16 and lost interest as I had to work for a living then... I did have a lot of fun, I wanted to make a Cottrell precipitation filter for a science fair project but I could never get project approval and I was only generating about 50 KV for the precipitator. A Cottrell Precipitator is an electrostatic filtering device used commonly as a smokestack filter for Really heavy industry like coal fired power plants and steel mills... There was A home device sold about 10 maybe 20 years ago called The Ionic Breeze. I still have a small one that works quite well in my bathroom, nice little breeze too. Enough at any rate to blow out a bic cigarette lighter.

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Yeah im lucky, tho I work full time I make enough to spend on these little projects, more recently more into the HV field, which is fascinating
Stuff like this is just plain amazing
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Purple streamers - as seen in every tesla sphere, colour is mainly due to nitrogen IIRC.  There is a test for leaks in vaccum glassware using a high voltage AC supply - any ingress of air will allow purple streamers to form near the leak.  As for explaining the detailed behaviour of a partially ionised gas, that's complex, a degree course in plasma physics would be a starting point !!

Take care with the high voltages BTW.
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Im lucky, heavy silicone application around the tube and wires llowed this to work without any leaks, the only leak I have is a shoddy connection to the pump, I just have the tubing pressed inside the hose
But those definetly aren't due to a leak, I just leaked out the air from the tube until they formed
Heres a pic nearly full evacuated, all you see is like a halo around the electrodes


* 2012-08-08_21-09-42_504.jpg (809.93 KB, 1840x3264 - viewed 12 times.)
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My only guess (and it's pretty far-fetched) is that whenever the oscillator turns on (1/60000 second) the resulting plasma pushes other particles away from the electrodes. Eventually they bounce around and line up into 11 stripes between the electrodes. Basically visible harmonic vibrations. I hope that's the answer because that would be awesome. Try changing the frequency if possible, they might go away.
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My only guess (and it's pretty far-fetched) is that whenever the oscillator turns on (1/60000 second) the resulting plasma pushes other particles away from the electrodes. Eventually they bounce around and line up into 11 stripes between the electrodes. Basically visible harmonic vibrations. I hope that's the answer because that would be awesome. Try changing the frequency if possible, they might go away.

Yeah it's probably an interaction between the frequency of the signal, movement of the charged particles, and perhaps the volume of the evacuated container all combining to form a standing wave.  However, IMHO, the ability to explain it does not detract from its visual appeal.
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