Advanced Methods for Investigating the Superheated State of Liquids Based on the Pump–Probe Principle

Dynamic methods for creating a superheated state of liquids and tracking their decay are presented. These methods allow relaxation characteristics of short-lived metastable states to be investigated across a wide range of temperatures and pressures. The relaxation of a medium is studied by a “probe” action after a short “pump” pulse. The concentration of the pump pulse in time and space allows the synchronization and localization of means for recording fast-flowing processes. Our aim was to carry out a brief review of methods for studying pulsed thermal processes in a superheated liquid based on the pump–probe principle by heating a platinum wire and releasing pressure in a bubble chamber. Although this article is a review in nature, we present new results obtained using the methods described. Non-stationary heat transfer to n-hexane with a water admixture was studied using the method of controlled two-pulse heating of a thin platinum wire. A water admixture of less than 0.01% increases the heat transfer of the probe by 10% at a sufficiently high degree of superheating of the base fluid. For uniformly superheated n-pentane, the dependencies of the refractive index and density on pressure and temperature were obtained using fiber optic densitometry. Using laser velocimetry, vaporization rates ranging from 4.8 to 9.5 m/s were obtained in the first microseconds of n-pentane boiling-up due to activation by a laser pulse in a bubble chamber at relatively low superheating (18–44 K).