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

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."

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.

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

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!

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

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 :)

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.

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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?

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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.

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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

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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.

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

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Originally Posted by planters

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.

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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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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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I hate it when someone with a little inside knowledge claims a NDA. It's a bit like saying I heard a joke,but I can't tell you. In this case, I do not have any NDA, but I have some insight that the source would probably not appreciate my distributing to the world. I'll PM you with some additional detail, but the general idea is that the diode is simply a high brightness light source. The fact that it is a laser is irrelevant. Consider pumping the crystal laterally and specifying the dimensions of the crystal to match the diode bar emitter face. Then, close couple the diode bar right into the crystal without any optics at all. If you want some stand off then a high index material (diamond would be ideal) can act as a light pipe because of total internal reflection. Or, specify a glass rod externally coated to reflect 808nm as a light pipe. These are somewhat exotic items, but not crazy expensive.

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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

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http://www.caddock.com/Online_catalo...h_voltage.html

I picked up a few of these on eBay.

I don't know if I would cut it open. Maybe you will have to. Depending on the energy, you can measure the capacitance with most multi-meters and this should agree with the stated capacity. Also, charge it to a hundred volts or so and see how quickly it drops its voltage. If very slow, then it might be worth investigating the defect. The major risk is that the dent might provide a voltage failure point to the case at a high enough voltage and this would obviously be more than be dangerous. My approach in dealing with storage capacitors and especially with the huge ones I use now is to treat the case (even though it is designed to be dead) as if it might at any point be at the full charge voltage. This means mounting so that the case is fully isolated. I do not ground this case because the huge energies discharging through ground (were it to happen) would probably be more than interesting.

Yes please do PM it would interest me.
So the diode basically would act as a flash lamp alternative reading this at first sight.
I read before that materials like ruby require the entire crystal to be blasted so a helix lamp is in place there as if there are gaps they will absorb a big portion of the released coherent photons.
This does sound really really interesting though and I wonder what wavelengths can be created from this!

You're right about ruby. This is not true for vanadate/YAG.

No, the diode would act as a CW light source. The two philosophies are a longitudinally pumped crystal with a smooth, bell shaped, axially positioned pump spot. The thermal distortion caused by the pump heating is symmetrical and the cavity optics are designed to compensate for this. The other philosophy is to saturate the crystal with lateral pumping causing a diffuse and hopefully homogeneous thermal expansion of the crystal minimizing the optical effects on the laser beam. Axial pumping is more efficient, but the power that can be launched is more limited and more expensive/watt.

What is odd and i have never had this happen with a capacitor is the case seems to float to about half of the input voltage and both caps do it, the ones i have are made by NWL Capacitor, they are both 160mfd at 2.5kv dc, they hold 200 volts but the case does not make sense, the one with out the dented side does the same thing. with an ESR meter there is no connection to the case but that's at 2 volts. Maybe what i am seeing is a capacitive coupling to the case and not a real fault
I have not used them in about 10 years so i dont remember if they did that before, I got them as unused surplus back in 2005
I will be treating them as being a live case and isolate it. I too have always treated beasties like these as having a potentially live case, i think i am going to put plexiglass around these.

Thank you for the link to the resistors, i know i have stuff like that around but i need to find them now, mine i think are made by the same company, i had gotten them for use on a tank for a tesla coil as it uses 20 polypropylene caps

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i am going to put plexiglass around these.

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Good idea. Assuming you will take these to a little under 2,500V then you will be putting in a little under 500J assuming they fully discharge during a pulse and they probably won't let's assume 400 J. Then, with a 6mmID lamp and 150J/cc then you need 2.7cc and this gives a 10cm electrode spacing. This might seem small, but that is where the magic happens.

Thank you for the info. I also had a second question about a power supply, my glassman unit is a bit temperamental at lower voltage as it's 0-30kcdv, my idea is to use a voltage break down voltage tester but i think it's out put is ac, i need to dig it out to day but what i was thinking is building a rectifier as it has only one output and ground unlike a neon transformer, what bugs me is i have a hipot tester with a load defeat so it wont shut down due to the higher load of recharging the caps, both are 1-2500vdc i am also watching a power supply on flea bay that's in my 10 dolor price range lol,

I am so happy that i can finally used this gear rather then just collecting dust, sure i am vulture of the electronics world but i generally wont throw something away unless it's beyond repair.

I made a divider last night thar does the trick, i dont have the resistors linked but plenty of other banded high voltage resistors, i fine tunes the low voltage side with a pot as my resistors have a larger tolerance, i could not find what i need on flea bay but i am looking, the set up i have a crude but has a accuracy now of +- of about 2 volts

Before they have to hold off 2,500 V and lots of joules, you want to test the divider to make sure the resistors will hold the voltage.

2,500V is not really that high. you might try a voltage multiplier run off 230V from your wall. A Cockcroft-Walton design could be set up for very little:

http://www.allaboutcircuits.com/text...e-multipliers/

A ballasted MOV off a small variac would be inexpensive and more than perfect. Full wave rectify this and you have as much power as you choose to use at voltages in this range.

I have built voltage multipliers in the past, i made a 10 stage one some time back and DLP style projection TV's use a multiplier as well to get around 340 or so volts for the sets ballast to power the UHP lamp, i still have one, when i actively repaired them i made a test rig so i could test customers lamps out side of the TV, I will start getting the parts together to build one as soon as i can I got the breakdown tester our of the shed today and in the process of cleaning it up and testing it, I also found a lamp that i forgot i had, check it out.
Attachment 48596

It came out of an old lighting fixture the military had, it's the only one i have come across that has the trigger inside the lamp as a 3rd terminal, it's a short arc xenon but have no clue to the ratings

I will test the the high voltage resistor, if memory serves i have tested them at a much higher voltage then needed for this project

I made a self contained digital meter with a 1000:1 divider all inside an old plexiglass box that uses an isolated battery for power, i found out the hard way that a second meter i was going to use was not isolated, the main resistor in it is rated to about 10kv so i can leave it sitting on the capacitor bank and act as a way to bleed off the caps.
I used a 10 turn wire pot to compensate for the crappy tolerance of the main resistor, on the low voltage side, it's also in the box for safety
Attachment 48597

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Originally Posted by masterpj

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

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Hello,
you can show my ablative air flashlamp from my dye laser Under : http://www.swissrocketman.fr/realisa...e,fr,3,222.cfm

You need a specific energy input between 200 and 1500 J/cm3 to have the ablative regime !
You can use for the external wall plexiglass 10 to 20mm in tickness

Attachment 48608

please correct me is i am wrong but my experience with plexiglass is it will block the short wavelength ultra violet spectrum, I use a sheet of plexiglass as the UV shield with my florescent rock collection that uses a UVC lamp.


Very cool stuff on your web site, thanks for sharing that
Like your dye pump, is that a roller pump? , if i ever get to that level of a laser i have a roller pump that used to be on a bypass machine, i managed to get 3 working pumps during my time at that employer, i used one to pump the fuel out of my water craft,got some strange looks from neighbors but it worked very well

drat the tubes i have are only 10cm long so i will need to lower the power a bit more, not much though i think as they are 6mm id, i may see if a friend of mine can machine the electrodes, he i think as access to a real lathe
I am going to try and fire the xenon lamp that i have on hand,i have posted it before i also found another little lamp
Attachment 48611
the spacing is about 17mm and has 4mfd 2kv cap on the back with it's trigger coil, it came from England but the person i got it from did not know what it was used for

sorry if this is drifting from topic but i love flash lamps :)

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You need a specific energy input between 200 and 1500 J/cm3 to have the ablative regime !
You can use for the external wall plexiglass 10 to 20mm in tickness

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Actually,the ablative regime begins when the silica and oxygen lines begin to appear and this occurs in low pressure discharges at about 35J/cm^3. With the appearance of the wall material there is also an increase in luminous efficiency. With small diameter lamps in the 1-2mm diameter range, the output begins to saturate at several hundred J/cm^3. With the larger lamps I have worked with in the 8-13.5mm range I have yet to reach any apparent saturation, but I'll work on it; I just received some REALLY big capacitors.

Plexiglas should work well although I haven't tried it. Despite the fact that it is a low melting point hydrocarbon, it is in fact the ablation products, whatever their origin, that are the source of the thermal radiation. The major downside of Plexiglas from my point of view is that it blocks UV. Depending on its particular composition and thickness this can begin as high as 300nm and is usually complete by 220nm. Unlike what I described as VUV absorption and re-emission by an ablating layer which should have nearly unity efficiency, UV absorption by the acrylic will likely be diffuse through its thickness and be manifest as heat. I down convert this UV into the dye absorbance band.

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drat the tubes i have are only 10cm long so i will need to lower the power a bit more, not much though i think as they are 6mm id, i may see if a friend of mine can machine the electrodes, he i think as access to a real lathe

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You are likely still OK. One paper I have shows that the 6mm lamp began to saturate at around 200J/cm^3. I wrote 150 as a conservative target.

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sorry if this is drifting from topic but i love flash lamps

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And arc lamps.

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I made a self contained digital meter with a 1000:1 divider all inside an old plexiglass box that uses an isolated battery for power,

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Very nice wok by the way.

Femtoman,

You also do nice work.

That blue hazy appearance to the lamp after 100 pulses surprises me. The ablation process cleans the lamps and when run at low energies the un-ablated electrode sputter tends to be black. Might this be some dye or sealant material.

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Originally Posted by planters

Very nice wok by the way.

Femtoman,

You also do nice work.

That blue hazy appearance to the lamp after 100 pulses surprises me. The ablation process cleans the lamps and when run at low energies the un-ablated electrode sputter tends to be black. Might this be some dye or sealant material.

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My flashlamp is a coaxial lamp and i work in the ablation regime at 500J/cm3 with very short pulse 500 to 600ns ( 2microFarads 25 kV)
In your video the flashlamp do not work in the ablating regime because the current intensity and the small surface not produce ablating regime (500 microfarads 3 kV) !
I have a discharge time 50 time shorter than you .
My flashlamp is optimised to pumping dye laser the annular section is 0.5mm thickness ( internal diameter 7mm and external diameter 8mm)
With long pulse more than 10 microsecond you have a glassing surface and with short pulse a thernisch surface!

Sorry my English is very bad!

To test my caps would you believe i went old school, very old school, Until i make the doubler for my main power supply i have been using a dynamotor I built a controller using the spare power supply from a PlayStation 3 and a pwm controller i had from another project, an unexpected advantage i came across is while the dynamotor is connected it discharges the cap bank when i ramp down the dynamotor, on 12 volts i get 425VDC. and on 24+ i can get 1kvdc but it stresses the thing.
the led read out is a cheap over seas made shunt to measure dc current draw, i still need to make a formal cabinet for it, the Dynamotor is just a classic cold war surplus, not that efferent but does the job
Attachment 48612


Femtoman, your English is just fine, no worries, it's even better then mine at times :)

my friend can indeed make the electrodes for me so all i need to do is makes the engineering drawings and supply him with the brass, it will take time but the work will be free, we barter , i fix his stuff and he can make parts for free, wish brings ip a question, i have been using the windows build in paint to make the drawings, is there anything free that works better then "paint" in a winblows platform?

Draco,
As long as he is setting up, you probably should ask for something like 6 electrodes. You never know, once you have a pair of flashlamps you just might want to light up a little dye.

Femtoman,


I am enjoying this discussion, but I have to disagree with you on several points. The wall ablation regime does indeed begin much lower than 200J/cm^3. This is supported in the literature where evidence of wall material begins to appear in the output spectrum and by analysis of the gas drawn out of the tube when operating in a flow through mode.

More than this, it can be demonstrated. Run a typical tube at low energies (below 20J/cm^3) for several hundred pulses. Observe the walls of the lamp near each electrode, especially if high erosion electrodes machined out of aluminum are used. There will be several cm of grey/black deposit that builds as the pulse count mounts. This material cannot be cleaned chemically, but a single higher energy pulse above approximately 50J/cm^3 will completely remove this material. If the tube is now run at this higher energy, the deposits do not return. This is why I questioned the tube in your image. It should be clean unless the material is not glass and the UV flux is causing some dye or other organic to be deposited.

Energies above 200J/cm^3 will be hard to achieve in real life tubes larger than 6mm ID. Indeed, in your coaxial tube with a 7mm OD inner tube and a 8mm ID outer tube which gives an annular gap of 0.5mm, multiplied by the tube length which I would estimate at 35cm gives a volume of approximately 4cm^3. Even at 500J you would only be at 125J/cm^3. By my measure you were well within the ablating regime, by yours, you were not much above 1/2 way to the bottom of the range.

Several decades ago when Russian researchers set the world record for a single dye laser pulse at 400J, they also used a coaxial lamp, however because of the large dimensions of their dye cell it may be that their lamp was not operating in the optimal loading range. They were using approximately 50kJ in an approximately 10us pulse. Based on some discussion by Duarte, it may be that the holy grail of short duration pumping may be less important than absolute peak power no matter the duration.

Although I suspect that pulse length has some significance it is not usually factored into the ablating threshold determination. It will most likely be that the shorter the pulse, the lower the transition from line emission to thermal radiation of wall products. I say this because a more rapid pulse will diffuse less into the bulk of the glass, reserving the energy and increasing the surface temperature. Nevertheless, I am seeing ablation in my 16us pulses.

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Originally Posted by planters

Draco,
As long as he is setting up, you probably should ask for something like 6 electrodes. You never know, once you have a pair of flashlamps you just might want to light up a little dye.

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I talked to my friend last night and he tells me that he can makes them i just need to supply him with the materials and make up a drawing, i have been using "paint" in windows but was wondering if there is a free version of CAD around? using paint works but the time it takes sucks.

I am almost positive he wont mind making more then one set, thanks for that idea!

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Originally Posted by Draco

I talked to my friend last night and he tells me that he can makes them i just need to supply him with the materials and make up a drawing, i have been using "paint" in windows but was wondering if there is a free version of CAD around? using paint works but the time it takes sucks.

I am almost positive he wont mind making more then one set, thanks for that idea!

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You can just use the old fashioned method of drawing a the design on a piece of paper, take a picture of the drawing and then send it too him.

As long as he will not be able to take your drawing and enter into a CAM program then I agree, just draw it up. This is just too simple. The only guiding measurements are the OD and the ID of the glass tube and the axial hole that you will tap for a hose barb. Expect this to be 16-27 NPT or a machine thread 10-32.

sorry i was making it more complicated then it is

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Originally Posted by planters

Femtoman,


I am enjoying this discussion, but I have to disagree with you on several points. The wall ablation regime does indeed begin much lower than 200J/cm^3. This is supported in the literature where evidence of wall material begins to appear in the output spectrum and by analysis of the gas drawn out of the tube when operating in a flow through mode.

More than this, it can be demonstrated. Run a typical tube at low energies (below 20J/cm^3) for several hundred pulses. Observe the walls of the lamp near each electrode, especially if high erosion electrodes machined out of aluminum are used. There will be several cm of grey/black deposit that builds as the pulse count mounts. This material cannot be cleaned chemically, but a single higher energy pulse above approximately 50J/cm^3 will completely remove this material. If the tube is now run at this higher energy, the deposits do not return. This is why I questioned the tube in your image. It should be clean unless the material is not glass and the UV flux is causing some dye or other organic to be deposited.

Energies above 200J/cm^3 will be hard to achieve in real life tubes larger than 6mm ID. Indeed, in your coaxial tube with a 7mm OD inner tube and a 8mm ID outer tube which gives an annular gap of 0.5mm, multiplied by the tube length which I would estimate at 35cm gives a volume of approximately 4cm^3. Even at 500J you would only be at 125J/cm^3. By my measure you were well within the ablating regime, by yours, you were not much above 1/2 way to the bottom of the range.

Several decades ago when Russian researchers set the world record for a single dye laser pulse at 400J, they also used a coaxial lamp, however because of the large dimensions of their dye cell it may be that their lamp was not operating in the optimal loading range. They were using approximately 50kJ in an approximately 10us pulse. Based on some discussion by Duarte, it may be that the holy grail of short duration pumping may be less important than absolute peak power no matter the duration.

Although I suspect that pulse length has some significance it is not usually factored into the ablating threshold determination. It will most likely be that the shorter the pulse, the lower the transition from line emission to thermal radiation of wall products. I say this because a more rapid pulse will diffuse less into the bulk of the glass, reserving the energy and increasing the surface temperature. Nevertheless, I am seeing ablation in my 16us pulses.

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Planters,

A good article is " High-Energy Dye Laser Pumped by Wall-Ablation Lamps" Applied Physics15, 191-196 (1978) from TT.Okada
and "Ablative Flashlamps for High Power Peak Power Dye Lasers" APPLIED OPTICS Vol.16 No.8 p2293 - 2296 from Y. Levy G.Neumann

you can see the luminescent Spectrum of a flashlamp D=5.5mm and L=150mm at 10 torr air pressure with different input energy.

At 12J you can show the typical line Spectrum from the gas (air)
At 85 J you have the lines fom gas +lines from the wall ablating (effectively you have juste the wall ablating effect start at 25J/cm^3)
At 421 J you have a continuous spectrum like a black body.

In my laser i have 2uF 25kV 625J and 2.9cm^3 that is 215J/cm^3 i preview to work with 6uF

I have an article from Russian that give value from 200J/cm^3 to 2kJ/cm^3 effectively the wall ablating process start at 25J/cm^3 !:mad:

The big problem with wall ablating tube is that at high energy the hot plasma is absorbant for the light emission that muss traverse the plasma column
and the best way is to have a lot of flashlamp with on reflector . I think a good value is to be in the 100 to 150J/cm^3 input energy:)

Arnold,
Those are good articles and I have them. Thank you for looking into this with such diligence. The high temperature plasma does absorb and re-emit the high energy photons as a black body. This process does not have a quantum defect and so the only manifestation is a prolongation of the emission process. The effect of the cooling (emitting) black body is that the light pulse duration depends on the wavelength you are measuring. In the article by Levy he notes that their pulse duration varied from 1.8 usec at 377nm to 3.4usec at 560nm. I measure my light pulse duration with a simple biased photo diode, however the EFFECTIVE wavelength may have a substantially shorter duration than my unfiltered measurement. This may also explain the "early termination" of flash lamp pumped, dye laser output. This property is blamed by many authors on photoacoustic disturbances from the pump pulse. Maybe it is simply that the usable pump light has simply ceased!

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In my laser i have 2uF 25kV 625J and 2.9cm^3 that is 215J/cm^3 i preview to work with 6uF

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This should be interesting. If you are already generating a substantial output, then increasing the pump energy 3x will probably generate more than an order of magnitude increase in output!

My laser produces large amounts of power and the problem is the optics. Well before I reach the limitations of the flashlamps, the cavity will need to be improved. I believe I now understand the principal behind unstable cavity optics. These are not intuitive, but they may act in the same way as a MOPA by selecting a small aperture within the gain medium and allowing the high quality, spontaneous emission generated here to be expanded to fill the medium for a single pass of amplification. You may need to go here as well.:)

i think i have scrounged up some parts to make a doubler for my project, i have 2 .2MFD 5kv caps and two diodes i had saved from a few microwaves , they should be over 2kv at about 600ma maby even an amp so i may need a current limit to the main caps, the main supply can and will do over 300ma at 2kv
That's my beast
Attachment 48649

Something to keep in mind if you plan to run at a significant rep rate. A flow through system will tend to "pump" the gas with the discharge. The brief period of high pressure drives the gas from the tube. You might consider using a solonoid to close off the vacuum line during the pulse. This is what I do. Alternativly, you can do what I did on my early systems. Use two solonoid valves each one attached to the gas supply and the vacuum line respectively. Then "T" this to the cathode/ground end of the tube. By closing one and opening the other, you can fill and then flush the tube. This allows you to trigger the tube without a separate circuit and the gas pumping is not a problem. Probably limited to one Hz with this system.

Oh, I forgot to mention that I like the PS in the kid's playroom. That worked for me as well.

Thank god i am the only kid allowed in my "playroom". I dont have kids near this place, when it comes time to visit my family i go to there home rather then here, more so with this new experiment and including my stuff with fireworks this is in my view the most hazardous device i have, i built the voltage doubler with what parts i have, it can clearly be improved but it does work, i charged one main cap to 2kv, i do need to install bleeder resistors, since i used a 1000:1 in the meter that does not provide enough resistance to self discharge in say less then 10 min, of course the fun way would be to just short it but i think that would damage the terminals lol
Harbor Freight (China Freight :) )has a sale on a cheesy drill press that i ordered so i will machine the brass my self, my other set up was lacking really bad, getting the part parallel is not going to work with what i have.
Thanks for the idea on using solenoids and since it does take a few seconds for my caps to charge i think that will work well

On a second thought the value of my caps in the doubler prevent an over current condition in my power supply

The problem with the gas "pumping" is that subsequent pulses can spontaneously fire because the capacitors reach voltage before the tube pressure reach its pre-pulse steady state. Dealexteeeme has a nice two channel pulse generator that will allow you to set up an automatic system.

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

Ok if i am interpreting this correctly I would use the timer to hold off the power supply that charges the main capacitors, or use it to hold off on the trigger pulse that would in turn fire the lamp.
I have two timers like the one posted , reading the manual for them is a nightmare due to the very horrible translation, the manual mine has calls the 8 segment led display (digital tubes),
trying other one i am trying to find documentation on it. The one i have running is an FRM01

on a plus both caps seem to be able to hold there rated voltage

I think i will put a little op amp inside the volt meter's case that will trigger an led when voltage is present on the main caps, the input to the meter is at a low voltage and i will use an amp op that can go to rail voltage from the internal battery just as an extra indicator that there is some voltage present, i am thinking of something simple but have not drawn anything up yet, i would love some ideas from you guys on this, maybe even a schmitt trigger even?

I came across an old Simpson milliamp meter and was wondering if this work work to monitor the charging current from the PSU to the doubler, it would be in it's own own plexiglass box so there would be nothing for the high voltage to bleed off to, like what i did with the panel meter a few posts op. My question would be if ti would be accurate as it has it's own internal shunt or would the electrical field at 1-2kvdc would make it inaccurate?

The timer I linked to does not have instructions, but the video is very useful in setting it up. You would use the timer to control the solenoids. Either to block off the vac line during a pulse or you would use it to switch the TWO solenoids in that alternating fill/flush method.

The E field shouldn't have any significant effect on the meter as the shunt across the meter is relatively low in value; provided it's well insulated from anything at ground potential, it should work OK.

how do you anneal quarts with out a kiln? when you mentioned fire treating the ends of then tube is to reduce scarp angles that could cause a weak point .
Is there away to anneal a tube in the oven?

No. To treat quartz you'll need high temps for both processes. The quartz supplier can do it or just understand that the explosion energy for your tubes will be lower.

Thanks, i will make the shield out of thicker material now

I dug these from the shed today, sady one the meter is frozen and i broke the torsion spring in an attempt to repair, i have never seen a panel meter with a torsion spring but i second unit had the meter sticking but that i fixed, these where from a ruby laser i missed out on buying a number of years back but the buyer did give these for me, my intent is to use as intented to remote charge and fire the flash lamp when i dont want to use the programmable timers
Attachment 48757

With the newer doubler worked out now i can charge the main caps at a 300ma rate so now it's time to construct a trigger, i have a few trigger coils but still not sure on how to trigger it with out burning it out, the trigger coil i want to use came with my 125mm xenon lamp, another option i guess i could use is a module that came from what i believe to be a stun gun, it runs on 3 volts and puts out about 30kvdc at an unknown current, more then enough to ionize some fun.

Eric, couldn't you still use an NST and only use one HV leg and ground? Not that I would ever use an NST but I was just wondering.