Kiseleva T.A.   Yakovlev V.I.  

Wave structure in a supersonic flow at different focusing of a pulsed laser radiation

Reporter: Yakovlev V.I.

A question of a choice frequency-energy parameters providing quasi-stationary wave structure (forebody shock wave, thermal wake) near optical breakdown in a supersonic flow is actual for researches using pulse-periodic laser radiation energy supply. According to calculation work [1] the decision obtained was based on strong explosion modelling for point focusing of radiation. It resulted in high requirements for pulse repetition frequency, which wasn’t succeeded in experiments, as for example in one of the first work [2]. For the first time a quasi-stationary energy supply in a supersonic flow was realized by experiments [3] using longitudinal laser beam focusing (laser plasma of cylindrical symmetry) along flow velocity.
Consideration of experimental results using CO2-laser energy supply at different laser beam focusing: longitudinal along flow velocity and point with a beam directed across flow [4] is presented in this work. Results showed that using point explosion in consideration of counterpressure model (cylindrical, spherical geometry) it is possible to determine relationship between pulse repetition frequency, energy and gasdynamic parameters, when quasi-stationary wave structure and thermal wake in a supersonic flow under optical pulsed discharge can be realized. Comparative analysis of peculiarities for stated focusing means in high velocity flow is fulfilled.

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