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Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Yeah, I'm also a bit skeptical if you made anything but just a complex triggered spark gap.
Capacitance of the lamp is significant and it becomes conductive when ionized.
Ionization is not strictly necessary to 'help' the ionization; electrostatic and kinetic energy will actually work together to produce a breakdown.
Simply heating the air to few hundred degrees C may be enough to decrease the breakdown voltage by like 2x.
Strong burst of UV may be able to do the same too, but you need to assure that it's only light in the path. I don't think this small lamp can actually do it.
Registered Member #10
Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424
Amateur-Scientist wrote ...
Is it the UV light causing the gap to trigger or the electric field from the lamp? It seems to me the UV intensity from the lamp is not strong enough to ionize air, but the electric field might. ..
I agree that this is unlikely to be due to UV but to the capacitative effects of a surge of 1200V HV high current pulse triggering the UV tube.
I challenge you to repeat the experiment with the UV tube covered with paper then uncovered. The same method of triggering the sparking could be used. Just attach the paper to a string and pull it out part way through. If it doesn't show that UV has an effect then you should admit this and rename your Youtube video.
The while the instantaneous power output of a triggering laser is quite large, it's actually not too formidable. I've seen at least one example of a Marx bank charged from a camera inverter-based power supply (~7.5kV IIRC) driving a TEA laser, which was then capable of triggering a spark gap from across the room (beyond the influence of any electrical fields associated with the laser discharge). But it's been a while, and I don't remember where I saw it . . . Google and ye shall find.
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
The power output of even a small TEA laser many KW, probably even several MW (capital M), and presumably focused in a pretty small area, as compared to this tube which is giving off about 10W of power, over the whole 8" by 360degree area of the tube...
Registered Member #195
Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111
UV light is ionizing radiaton and I believe creates free electrons as it striks a surface. triggered gap technology is old science. We prduce them at my work and I am makeing 20 of them now at work. when some of theas home made marxes go off the UV from one stage helps trigger the next
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
Tesladownunder wrote ...
Amateur-Scientist wrote ...
Is it the UV light causing the gap to trigger or the electric field from the lamp? It seems to me the UV intensity from the lamp is not strong enough to ionize air, but the electric field might. ..
I agree that this is unlikely to be due to UV but to the capacitative effects of a surge of 1200V HV high current pulse triggering the UV tube.
I challenge you to repeat the experiment with the UV tube covered with paper then uncovered. The same method of triggering the sparking could be used. Just attach the paper to a string and pull it out part way through. If it doesn't show that UV has an effect then you should admit this and rename your Youtube video.
TDU
I see that for most of you is hard to believe that the UV is the direct trigger. I still believe it is but I have to add little bit more info why. First the two electrodes are very close to spontaneous triggering (it is a question of 2mm shift and the spark gap would work by normal spontaneous air breakdown). Next UV light is strong ionization agent – it kicks out free electrons from molecules of the air (it produce ozone) and most likely also from the glass which the tube is made off. Also the argument about the low power of the tube is weak. The 1200V pulse from the quadruplerm is very short and has quite high amp peak – sorry I’m notable to count it exactly (maybe somebody here can count for me at least the energy of the pulse). And finally I’m operating relatively big home made Marx generator which I’ll post soon in the project section. Here I can see that the spark light which comes from the spark gaps during the shot is really not high. I have some pictures ot the triggering events of Marx so check it out…
However during this weekend I’ll make more experiments you have suggested…
Here are two folowing snapshots of the trigeering of my old Marx. You can see that the initial spark in the lowest spark gap has relatively low energy.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Mates wrote ...
However during this weekend I’ll make more experiments you have suggested…
Here are two folowing snapshots of the trigeering of my old Marx. You can see that the initial spark in the lowest spark gap has relatively low energy.
Marx gen is not triggered by UV, as the first gap fires the voltage across the second one doubles and so on
Registered Member #514
Joined: Sun Feb 11 2007, 12:27AM
Location: Somewhere in Pirkanmaa, Finland
Posts: 295
jmartis wrote ...
Marx gen is not triggered by UV, as the first gap fires the voltage across the second one doubles and so on
Well yes, but the UV helps ionize the gaps and allows the Marx to trigger faster. Or something.
I too think that the UV from that bulb doesn't have enough power to ionize air. A spark gap (like in a marx) can give a multi kilo(mega?)watt pulse, so thats different.
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
Christopher Miles wrote ...
The only thing I am suspicious of is the bulb is not a real short wave UV bulb. I thought most of the energy used in this type of experiment is short wave UV? Glass blocks a great deal of the short wave, so a bulb used for short wave is made of quartz. I use these types of UV tubes in my salt fish tanks to keep the bacterial down. The bulbs are super $ due to quartz and they are clear. They will burn your eyes, and produce ozone. Very nasty UV indeed. A bank of them can be used to keep the bacterial down in a swimming pool.
The UV in that little tube does not have enough energy to do much indeed.
Cheers, Ch
The tube used in this experiment is also expesinve quartz glass made (the price is around 100$). It is originally from detector of DNA separated on agarose gels stained with ethidium bromide. It has a peak emission at 302 nm...
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UV triggered spark gap is working!!!
