Editorial for the Special Issue on Advanced Materials, Structures and Processing Technologies Based on Pulsed Laser

Pulsed lasers are lasers with a single laser pulse width of less than 0 [...]

Hydrodynamic simulation of laser-induced shock waves using the Turbulence Problem Solver software package

The problem of irradiation of a semi-infinite bulk metal target by a single laser pulse, being important for many lase technology applications, is considered. The model for simulating the propagation and attenuation of shock waves, occurring when metals are irradiated with single laser pulse, is presented. The paper describes the computational algorithm based on the model and features of its implementation in C++ in a software package Turbulence Problem Solver (TPS) for modeling a wide class of problems described by hyperbolic equations. The problem is modeled using different approaches and the results are compared. The object-oriented polymorphic architecture of the software complex accelerates and facilitates the process of model development and calibration, allowing for flexible configuration and combination of elements of numerical models: Riemann solvers, various types of and reconstructions, and equations of state of matter.

Surface Morphological Features of Molybdenum Irradiated by a Single Laser Pulse

Molybdenum (Mo) is considered a plasma facing material alternative to tungsten (W) for manufacturing the divertor armours of International Thermonuclear Experimental Reactor (ITER). Transient thermal loads of high energy occurring in a tokamak during the service life have been simulated through a single laser pulse delivered by a Nd:YAG/Glass laser, and the effects have then been examined through scanning electron microscopy (SEM) observations. An erosion crater forms in correspondence with the laser spot due to the vaporization and melting of the metal, while all around a network of cracks induced by thermal stresses is observed. The findings have been compared to results of similar experiments on W and literature data. The morphology of the crater and the surrounding area is different from that of W: the crater is larger and shallower in the case of Mo, while its walls are characterized by long filaments, not observed in W, because the lower viscosity and surface tension of Mo allow an easier flow of the liquid metal. Most importantly, the volume of Mo ablated from the surface by the single laser pulse is about ten times that of W. This critical aspect is of particular relevance and leads us to conclude that W remains the best solution for manufacturing the armours of the ITER divertor.

Метод лазерной колорации в экспериментах по филаментации одиночных импульсов и образованию световых пуль в однородных прозрачных диэлектриках

The advantages of using the method of laser coloration for investigation of specific features of filamentation in homogeneous transparent dielectrics are described. The results of several experiments conducted with a lithium fluoride crystal by this method are presented. The possibility is shown of obtaining data on the structure of the light field in a filament formed by a single laser pulse and processing them at a substantially later time after the experiment, which is not available by using other methods, allowed observing a plasma-free regime of filamentation, detecting single-cycle light bullets, and demonstrating their robustness.