Millisecond laser spark in gases

An investigation was made of the optical breakdown of gases by millisecond spike pulses of λ = 1.06 μ laser radiation. The breakdown in air was due to the presence of giant nanosecond spikes in the structure of millisecond pulses produced by a laser with a KGSS-3 neodymium-glass active element. Microsecond spike breakdown in argon at relatively low pressures of p < 10 atm was observed when the radiation was generated in GLS-1 glass elements. The investigation included high-speed photography, oscillography of the light produced by the spark, and measurements of the absorption of the incident laser radiation by a steady-state spark plasma. The absorption data were used in the determination of the range of temperatures and densities suitable for the experimental diagnostics of spark plasmas.