Bubble Glow at Hydrothermal Vents as the PeTa Radiation

The paper presents a physical model of a natural phenomenon, the glow of bubbles at hydrothermal vents formed during underwater volcanic activity. The basis of the model is characteristic non-equilibrium radiation under first order phase transitions that since 2010 has been referred to as the PeTa (Perelman-Tatartchenko) effect. This is the fourth paper in a series developing the model for similar physical phenomena: cavitational luminescence (CL), multi-bubble sonoluminescence (MBSL), single-bubble sonoluminescence (SBSL) and laser-induced bubble luminescence (LIBL). The previous three papers were published during 2017-2018 in this Journal. In the third one we have shown that above mentioned physical effects can be generalized as a phenomenon that we have titled “Vapour bubble luminescence” (VBL). VBL is very clearly represented in a non-equilibrium phase diagram. The essence of VBL is as follows: when there is a local decrease in pressure and/or an increase of temperature in a tiny volume of a liquid occurs, one or several bubbles filled with vapour will appear. Subsequently a very rapid pressure increase and/or temperature decrease in the same volume of liquid leads to supersaturation of the vapour inside the bubble. Upon reaching critical vapor density, instantaneous vapour condensation and emission of the phase transition energy that is accompanied by a flash (this is the PeTa effect) results in a sharp pressure decrease and the bubble collapses due to the pressure drop. This process is accompanied by a shock wave in the liquid. A similar effect occurs if bubbles filled with hot steam, for example from a cappuccino machine, are injected into a relatively large volume of cold water. The VBL model explains all experimental data concerning CL/MBSL/SBSL/LIBL and the relatively new natural phenomenon, the glow of bubbles at hydrothermal vents. Several model experiments demonstrate the PeTa effect under similar conditions. Additionally, we define the PeTa effect in all its manifestations on a non-equilibrium phase diagram. This clarifies which niches can contain VBL processes. We also demonstrate the window of transparency (WT) for the PeTa radiation during crystallization of a supercooled tellurium melt and propose the design of a cavity-free pulsed laser on the basis of similar crystallization processes.