Publication details

Automated determination of pressure profile generated by discharges in contact with liquid phase by interferometric technique



Year of publication 2019
Type Conference abstract
MU Faculty or unit

Faculty of Science

Description The development of discharge in dielectric liquids is still centre of discussion to this day. The propagation of streamer is closely accompanied by time-dependent radial expansion of pressure wave in surrounding liquid. The phenomena of shock waves produced by expanding corona-like discharges in aqueous solutions is well known, nevertheless the determination of pressure profile of investigated inhomogeneity can be quite challenging (eg. [1]). To investigate aforementioned discharges in distilled water or highly conductive salt aqueous solutions the Mach-Zehnder interferometer is used to reveal fast micro-physics by study of change of refractive index. Consequentially, the distribution of pressure and electric field generated by nanosecond high-voltage pulse in water can be estimated. To effectively achieve these distributions, we propose the use of automatized procedure to analyze large amount of experimental data by advanced statistical techniques. An example of interferogram used in this work can be seen in Fig. 1. The evaluation of interferometric images is based on isolation of constructive interference pattern and ability to select individual light rays, see Fig. 2. As the light ray propagates through inhomogeneous region the deviation of refractive index is determined by ”onion-peeling method”. The method separates investigated inhomogeneity into several layers where the resulting distributions are achieved by iterative procedure. Result of such evaluation can be seen in Fig. 3. The results of automatized process will be critically compared with standard approach to evaluate its precision and improve it further. Ultimately we believe that this approach will lead to novel insight into the phenomena of nanosecond discharges in liquid environment and significantly increase the efficiency of experimental data evaluation. This contribution is funded by Czech Science Agency grant no. 18-04676S.
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