I got the TEA N2 laser put together in its original form, well. Somewhat, at least electrically it’s all in form. The thyratron is working great as well as the trigger circuit but the laser will not lase. It occasionally arcs over the electrodes, but it’s not producing a proper discharge. I think something is wrong with the pre-ionization of the channel so I need to rip the bore apart and double check the pre-ionizer electrodes for any obvious arc-over damage and possibly try to rebuild them.  Most of the triggered thyratron pulses did not set off any kind of a discharge, a few did however.

TEA N2 Laser on Workbench

TEA N2 Laser on Workbench

I took about 10 minutes of video and put all the arc-over segments right next to each other so you can see them. The video is about 10 seconds long.  You can watch the video embedded below.

Down below you can also see a couple of stills I pulled out of the video.  Maybe better luck next time, I need to order a roll of Kapton tape to better rebuild these pre-ionizer electrodes. The PI electrodes also double as PI capacitors, using Kapton tape to build up layers between the PCB of the PI electrode and the primary electrode.

TEA N2 Laser Arcing Over

TEA N2 Laser Arcing Over

N2 Misfire – End of Bore

The big block of acrylic below is because I don’t trust old electrolytic capacitors and I wanted to have a shield in case it decided to destroy itself. While the blocks a bit overkill, it is what was handy.

TEA N2 Laser on Workbench 2

TEA N2 Laser on Workbench 2

I’ve updated the schematic from the original version, it’s still missing the trigger board for now though.  The changes I made were to move the inductor on the cathode to the right position and to add a ground to the grid/ground plane of the capacitor. The setup is ‘grounded grid’ thyratron, I bet it would help if I actually showed the grid ground

TEA Nitrogen Laser Schematic Partial

TEA N2 Schematic 0.1

Below is a video of the laser firing off in consecutive misfires, you can see that’s it’s misfiring as an arc and not lasing.  I’m one step closer however, now I just have to figure out how to make the pre-ionizers work properly.  Once I get this laser working properly I will probably switch to a rectified neon sign transformer for the power supply and use one of my EG&G TM-29 thyratron drivers.  I should be able to integrate it okay with some modifications to the existing drive circuit.


Similar Posts:

Share

Tags: , , , ,