Flashlamp Video

[planters]

I just completed a new video describing some techniques for constructing your own flash lamps. You can choose to fill them with a variety of gases and at different pressure levels. Because these are flow through tubes, the vacuum requirements are minimal. You can trigger them with an external wire, over voltaging with a switching element such as a spark gap or even intermittent pump down to reach a low enough pressure that they spontaneously over voltage.

Despite their seeming simplicity, there are some interesting physics taking place when these are operated at low pressures and very high energies. The explosion energy for these lamps is somewhere north of 150% of the accepted standard for medium pressure flash lamps (the usual xenon flash lamp pressure range in commercial lamps). The lamp impedance is around four times lower than commercial lamps allowing them to reach much higher peak output powers. The resulting high color temperatures require special techniques when taking advantage of these lamps to drive high performance lasers. I'll discuss that in a future video.

Thanks for watching.

https://www.youtube.com/watch?v=zI_1bH4yabk

 

[Mattronium]

Great! Thanks for letting us know.
Your videos are always very enjoyable.

And now that I've typed this, I'll watch the video.:tinfoil:

 

[ultimatekaiser]

Intriguing Planters....Wonder what the lifetime on them is. I imagine they'd have higher performance, but lower pressure would cause a faster loss of gas and lamp integrity. much like Ion lasers, I'd think it would suffer sooner. would be interesting to see a comparison of their lifetimes and comparative cost vs performance, as I believe the commercial lamps are made higher pressure to help extend their lifetimes under stress. Thoughts?

 

[Apocalypse]

I've always enjoyed your videos and this one is also very interesting.

I just recently watched your video from 2 years ago about building 532nm DPSS lasers. Did you have any success Raman shifting the 1064nm line to get yellow and orange?

 

[gozert]

Great video! I don't know too much about flashlamps, but this video for sure teached me a thing or two. Subscribed to you as well, can't wait for your future videos.

 

[planters]

I did get the raman laser operating by using the vanadate crystal itself as the raman element. The output powers were not impressive. 9W goes to 20-100mW when converted to raman. I am sourcing a coating company that will coat a CVD diamond as a separate element and this should greatly unload the vanadate from the raman generated heating.

NO, the commercial lamps use higher pressure Xenon to provide enough atoms in the discharge path to generate sufficient light. As the pressure drops with whatever gas, the output efficiency drops. At low pressures. electrode sputter also becomes a problem because the ions have a longer mean free path and get up to higher velocities before they slam into the cathode.

Lifetime is highly dependent on the peak discharge power (to the eighth power!). I am fairly certain that because of the low initial pressures these lamps have less mass accelerating at the wall for a given energy (energy equals M V^2, while momentum equals M V). I have yet to explode one of the lamps I demonstrated in the video at the same energies that destroyed the commercial lamp I showed you (4,000J). And, this is at four times the peak power because of their lower impedance. Because these are not sealed lamps, gas depletion and contamination are not an issue.

I converted my large dye laser from Xenon to these ablating lamps. The threshold voltage for the laser is substantially higher with the low pressure lamps, but the energy crosses at about 3 times threshold and then the gain is crazy steep. At 9kv a few mJ out, At 10 kV pretty bright. At 11kV too bright to look at. At 12kV the pulse feels hot. At 14 kV the output coupler explodes! The maximum usable voltage for the electrical system and the lamps is...21kV.

https://www.youtube.com/watch?v=fbIfVEboAzg

 

[ultimatekaiser]

Ah, no I get it now, though you pointed out what I was referring to about the lamp integrity, like the electrodes breaking down. but I watched only part of it in a hurry as i was at work at the time. I watched over it again, and it makes more sense to me now that I can see it in more detail. I missed the fact that it was an open/flowing system. I may have to share this with a friend...He really digs this kinda stuff. I don't have any flashlamp lasers currently, but I'll have to keep this in mind. Thanks for sharing either way. That's a heck of a setup. Far more than I have the money or space for currently.

 

[Pic1]

Very cool video. I have never delta was th flash lamps before, but it looks like a great project.

Vince "Pic1"