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Registered Member #3271
Joined: Mon Oct 04 2010, 02:29AM
Location: Canada
Posts: 159
I have done so as for a demo in the 70s. We had a double copper cladded fiberglass board about 1msq. Etched about 3cm of the copper all around the edges top and bottom (to prevent arcing) and about 1cm in the middle on one side along the optical "cavity". Two transverse rails of Al on each sides and a plexiglass sheet on top to feed the N2 and prevent the N2 from escaping. I used a flyback supply of about 20kV DC (that I still have). It would charge the PC board capacitor until it discharged. We doubled the power with a simple flat back mirror. The N2 laser gain was sufficient to lase (ASE really) without any mirrors. I can find more details should you want. Length was a bit over 1/2 m. At max power it could emit a beam with atmospheric N2. If I remember correctly the whole thing was based from a Scientific American article or something of that nature.
Registered Member #3271
Joined: Mon Oct 04 2010, 02:29AM
Location: Canada
Posts: 159
I'll see if I have notes from the project (mid 70s!) Looking at your pix my first impression is that you are missing the large pb board capacitor. The geometry with the pc board and laser gap built in was to maximise speed for the discharge. your schematic is pretty much as I remember but the geometrry is not. Also we injected pure N2 in the gap and contained it with a sheet of plexi so the N2 could only escate at each end. Eventually got it going iin atmosphere but only with meter lenght cavity. Nice addition with the adjustable gap. I'll see what I can dig up.
Registered Member #540
Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969
I'm thinking that you head the discharge at the ends since you didn't round the edges of the rails. The sharp corner lowers the breakdown voltage in that area and so the discharge stays there instead of being along the length of the cavity.
Registered Member #3271
Joined: Mon Oct 04 2010, 02:29AM
Location: Canada
Posts: 159
Indeed the two electrodes were rounded off and polished to a radius of about 0.8 to 1cm in our version. They were then positionned to get the best uniformity of discharge and ionisation. That was different depending on the N2 flow. Here is a link to an almost identical laser:
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