A single-filament schlieren method for flowing characteristic measurements in the pulsed gas lasers

Abstract

The single-filament schlieren method was based on the beam deflection in non-uniform medium. In this paper, a fourelement photodiode was used to acquire the deflection of the probing beam. The effects of electromagnetic interference (EMI) and the vibration of the blower on the output of the photodiode were investigated in detail and they have little impact on the measurements of the flowing characteristic after discharge. Then the perturbation in the discharge region was investigated. The heated gas in the discharge region can be easily detected and the gas velocity can be calculated by tracing the drift of the heated gas. This method also showed a high sensitivity and convenience to observe the acoustic waves originated from fast energy deposition. The results showed that the reflective acoustic wave existed for about 4 ms after discharge and it had a major effect on the non-uniformity of gas medium before the subsequent pulsed discharge.