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Thread: Flashlamp Video

  1. #1
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    Default Flashlamp Video

    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

  2. #2
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    Another fascinating lucid video! Can't wait to see the laser in the back in operation!

    Your flashlamp brings back memories of a Amateur Scientist article in Scientific American, February 1970, "A tunable laser using organic dye is made at home for less than $75."

  3. #3
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    I built that amateur laser just after the article was published and after it sent a beam down a hallway, I was hooked on dye lasers for life. The lamp in that article was identical to the ones I describe. At the highest energies these lamps will generate X rays.

  4. #4
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    Thank you for that video,
    I have tried making flash lamps in the past and they had a very short life, what i lack now is access to machine tools so i can't make the ends.
    One odd thing that i learned was glass in a liquid state is conductive

    What i use the tubes for is to act as a switch to some other device so low resistance is also needed but that hobby is currently inactive, i did finaly repair my power supply and have all the other equipment just no way to make the ends. this all originally was planned to make a large flash unit for wild life photography at night, the idea was to leave the shutter open and trigger the lamp and illuminate a very large area but that was shelved as all the equipment is far from portable.
    The only gas i can get currently is argon but that i think would work after watching that video, the argon was originally for my wire welder as a shielding gas for welding aluminum
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

  5. #5
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    If you want to experiment without a lot of equipment, you can make some poor electrodes in a drill press. Argon works very well.

    https://commons.wikimedia.org/wiki/F...hen_Curves.PNG


    It has such a low hold off voltage that for a given voltage you can fill the tube with more gas. At more reasonable power levels, more gas makes more light. But... I have some really big Aerovox capacitors and with these and 4 really big tubes the light should illuminate the landscape at one Sun at 1Km!

  6. #6
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    I love this. I have always wanted to learn more about the flashlamp pumping. I know a little bit about it but not enough. Usually had to deal with pictures or text from sams faq or some videos which really do not show the whole construction properly. I also really like that fact that you show an alterntive to xenon. Although on ebay I do see some xenon flash tubes which do look rather affordable to experiment with *if the glass is of the right type*. Thank you so much, maybe I will try to experiment with flash tubes sometime.

    Will you ever do a video on ramen shifting? or are the optics/crystals for this too exotic and too expensive to even think about obtaining?
    What else would be interesting would be the optical train (hope thats the right word for that) for correction these diode bars. They always look attractive but sourcing their optics is ...uhmmmmm

  7. #7
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    I have two high voltage caps outside i am going to retrieve, one has physical damage to the case so i may need to cut that one open and repair it, they are not as good as Aerovox, some moron damaged them them when i had them in an outside shed, i was one heck of an angry dragon then, the people responsible had no clue to what these things cost. i should beable to get a few thousand joules from them and give me a starting point to experiment from. i will try using a drill press, i think i can dig up a press vise that has 2 axis movement.
    The power supply i have is 0-30kvdc at 6ma, it has two very nice meters on the front of it as well
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

  8. #8
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    For the electrodes, I would start with brass. This will be the easiest to machine if your going to use the drill press. Don't worry about tooling marks and so go with a narrow, sharp tool mounted in the vise. Does the press have a drilling depth stop? If so, you can use that to control the cut when making the deep cut that forms the shoulder. If not, you can set up a block that lets the brass electrode stop itself.
    You might want to use a capacitor that will give several hundred joules at about 1kV. This should be enough voltage for up to 1/2 M electrode spacing with a typical roughing pump's ability.

    Another nice thing about DIY is that once you get it going, you can change the tube length from a few cm to 100 cm in length for additional power while still using the same electrodes. Lamp impedance is inversely proportional to the cross sectional AREA not diameter and proportional to the length. You can use this to control pulse duration. Self cleaning ablation begins around 25J/cm^3. This is also where your blue argon starts to look white and from here up the output efficiency increases rapidly. At around 150/cm^3 these lamps are as efficient as xenon.



    Will you ever do a video on ramen shifting? or are the optics/crystals for this too exotic and too expensive to even think about obtaining?
    Yes, I will. The DPSS laser I built can operate as a raman laser using the vanadate crystal itself as the raman shifting crystal. All the coatings had to be changed and the power was not impressive. I had decided to proceed with an independent raman crystal using CVD diamond in the angled portion of the "Z". The diamond has become very affordable, but drop shipping for the custom coating has not. That is where I stand. But, I will get to it.

    What else would be interesting would be the optical train (hope thats the right word for that) for correction these diode bars. They always look attractive but sourcing their optics is ...uhmmmmm
    If you are looking to use these as optical pumps then it might be interesting not to image them at all, but to use a scattering light pipe to bring them to the face of the pumped crystal. This is a little like the homogenization that occurs in the fiber, but at the cost of some inefficiency, this would allow much higher powers to be launched for low cost.

  9. #9
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    For the voltage divider you have on your capacitor, whats the value of the resistors you used?

    I noticed a problem with the caps that i own and may lead to a spectacular failure, one has a rather deep dent on it, trust it at lower power but it's effectively untested at the rating of 2.5kv, the dent is almost 1cm deep, I am thinking about cutting it open, that as a last resort though
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

  10. #10
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    Quote Originally Posted by planters View Post
    If you are looking to use these as optical pumps then it might be interesting not to image them at all, but to use a scattering light pipe to bring them to the face of the pumped crystal. This is a little like the homogenization that occurs in the fiber, but at the cost of some inefficiency, this would allow much higher powers to be launched for low cost.
    As of now searching for a scattering light pipe the only thing I get is images of fibers bouncing the beam up and down inside of the fiber or at max a Cylindrical light pipe.
    Where would I find such a scattering light pipe?

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