An industrial X-ray tube (ISOVOLT 450M1/25-55 from GE Sensing & Inspection Technologies GmbH) was used for the bubble visualization experiments (Fig. 3a). The high power ISOVOLT X-ray source operating with a maximum voltage of 320 kV and a current of 14 mA generates a divergent polychromatic X-ray beam. A scintillation screen (SecureX HB from Applied Scintillation Technologies) is attached to the surface of the container. The non-absorbed part of the X-ray beam comes upon to this scintillation screen where its intensity is converted into visible light. The further imaging is completed with a lens system (Thalheim – Spezial - Optik) and a high-speed video camera (Pco.edge from PCO) equipped with a sCMOS-sensor.