Xenon flash lamp (to excite DYE in LASER)

[9a3daa]

I am using L-6070 Glass Flashtube 6.0x70mm, Data sheet say that Max. Flash Energy is 100J for this tube. I use one layer air coil inductor with winding pitch. Calculator say cca 15 uH. Body is cheramic, diameter 29mm and 36 turns copper wire 1.1mm. Lenght of winding is 55mm. Capacitance is 1540 uF total. It's 7 capacitor in paralel (220uF/450VDC) and calculator say that energy is 100J@360V I can't find calculator for pulse shaping network, and my question is - is my setup ok? Do I need more inductance and less capacitance, or just less capacitance, because I don't want destroy tube. I use a flash lamp to excite DYE in LASER. Thanks for any help!

 

[filip.amator]

The most important thing wile pumping lasers with lamps is to achieve short duration of the pulse - an order of ns.

 

[FvM]

You hardly get discharge times below several microseconds with regular xenon flash lamps (with small foil capacitors and low inductance circuit). For the shown capacitor setup, rather expect up to milliseconds. Don't know if it's appropriate for the planned laser application.

 

[9a3daa]

I am planning to buy Low ESR capacitor and appropriate flashlamp just for laser pumping. This is just experimental setup Not final. I just dont know how to achieve flash duration in nS. How to calculate LC pulse forming network?

 

[FvM]

I don't see a "LC pulse forming network" in your (and any similarly designed) circuit, just a series L to reduce the peak current and respectively increase the pulse duration. For minimal pulse width, you don't want to use a series inductor and rely on flash lamp capability to stand the peak current.

I guess that xenon heat capacity doesn't allow sub-microsecond pulse duration anyway.

 

[c_mitra]

Use high voltage but low capacitor values to get short flash duration. It really does not matter for photography (us vs ns) but for lasers you need to pump as much energy as possible in the first few ns time scale.

Always keep some headroom, if the flash tube is rated at 100J, do not use more than 50J (or even less) per pulse (with a very low pulse rate). Remember than 1J/1us is only one MW in power. Laser excitation efficiency is usually low but if you get 10% conversion, consider that excellent.

 

[c_mitra]

I am planning to buy Low ESR capacitor and appropriate flashlamp just for laser pumping.

I do not see where is the dye cell located; perhaps it will be nice if you use 3-4 flash tubes symmetrically placed around the dye cell. Remember that the light from the flash will be absorbed most near the edge of the dye cell AND that is not the optimum point for the laser action.

Higher voltage and lower capacitance do give shorter pulse duration for the same energy. You also need to consider the dye concentration so that lot of excitation does take place near the center of the dye cell.

There are several other aspects to consider but your diagram does not show much.