DIY Home made High Performance TEA Nitrogen Laser and Dye Laser! - Les' Lab
Tear down of the DIY High Performance TEA Nitrogen Laser, how to build it and advice! - Les' Lab
Home Made 30 kV ZVS High Voltage Power Supply and Tear-down - Les' Lab
As explained in the wiki article on TEA lasers, the need for short pulses is to avoid arcing. At atmospheric pressure, a homogeneous discharge will become a loclized arc, which will fail to excite the N2 molecules along the whole length of the cavity. Also, ± homogeneous pre-ionization is essential.