Nitrogen Laser Emissions of Short and Long Durations Generated in Air

This article describes two sets of experiments. An eight-stage, pulse-forming network (PFN) Marx generator of 50-Ω internal impedance produces a “square”-shaped voltage waveform and induces multiphoton ionization, excitation of molecules and ions to generate laser pulses of long (<; 3 μs) and short (~10 ns) durations in air, when the principal laser line of the N2 laser at 337.1 nm was observed. The visible blue laser lines coming from the first negative band of N
₂
⁺
ions due to the B
²
Σ
_u
⁺
→X
²
Σ
_g
⁺
transition at 391.4 and 427.8 nm were studied. The wideband (300-800 nm) Schott BG 39 interference filter was also employed to examine whether some other lines participate in the emission being generated. The scaling law was derived describing the attenuation of the emission versus the distance for long-duration pulses (<; 3 μs) at 337.1 nm. The second set of experiments was introduced to support the data obtained. It offers information pertinent to the visible blue line emissions as well as to the photoionization processes, lighting phenomena, and processes occurring at high altitudes.