How Can I Build a Nitrogen Laser and Prove that It Can Lase

The objective: The purpose of this project was to construct a Nitrogen laser, determine which types and arrangements of components work best, and prove that it can lase. There are two types of Nitrogen lasers: the TEA, which operates at atmospheric pressures, and the low-pressure, which operates at lower than atmospheric pressures. I hypothesized that the TEA laser would work better with stiff aluminum plates as capacitors, rounded edged electrodes, and about 7000 Volts of power. I expected it to be more difficult to achieve lasing with the TEA laser.

Methods/Materials

I first built the TEA laser with materials I had on hand and tested it with only 3,000 Volts. I observed the arcing at the spark gap and between the two electrodes in the laser channel, modified components to improve the arcing #- I wanted to see as much arcing between the electrodes as possible -- and retested until I saw evidence of lasing. Then I attempted to prove lasing by photographing the dot, attempting to diffract the dot through a grating, and watching what happened to the dot when I moved the paper further away. After many tests and modifications to components, the TEA laser finally worked. I used most of the components from the successful TEA laser in the first test of the low-pressure laser, but I used a sealed electrode channel in place of the TEA electrodes and connected the channel to an old refrigerator compressor. The low-pressure laser worked during the first test.

Results

The TEA required sharp electrodes, a transformer that produced 7000 volts, and large aluminum foil capacitors. The beam from the low-pressure laser was smaller and brighter than the beam from the TEA laser. There was more arcing all along the sealed electrode channel.

Conclusions/Discussion

The results disproved my hypothesis that the best TEA electrodes would have rounded edges and that the best capacitors would be stiff aluminum plates. Aluminum foil made a better capacitor, because static electricity caused the top plate to stick to the bottom plate without leaving air pockets. I think that the rounded electrodes did not work because the arcing could happen anywhere along the height of the electrode edges. Since there was less gas in the low-pressure tube, the arcing was able to excite a higher percentage of it.

The purpose of this project was to construct a Nitrogen laser, determine which types and arrangements of components work best, and prove that it can lase.