Laser diagnostics of ultrasonic outgassing of an insulating liquid

The efficiency of hydrogen evolution from transformer oil into a vacuum and into air under normal pressure is studied for the case when the oil is exposed to focused ultrasonic radiation. The study is performed by the method of spectroscopy of biharmonic-pumping coherent anti-Stokes Raman scattering (CARS) based on stimulated Raman scattering (SRS). Ultrasonic radiation at a frequency of 1.76 MHz is excited by a spherical piezoceramic transducer mounted on the bottom of the vessel and is focused on the surface of the oil. This causes the intense stirring of the oil with the formation of a fountain. The room-temperature diffusion coefficient of hydrogen in the transformer oil, 10−7 m2/s, is found by approximating experimental data by a theoretical relationship for hydrogen evolution into air. It is shown that ultrasonic radiation with a power density of 2.2 kW/m2 accelerates diffusion processes ten-to fifteen-fold.