Подземный сток в таёжной зоне Западной Сибири: многолетние изменения и их причины

Проведён расчёт среднемесячных и среднегодовых значений подземного стока в таёжной зоне Западной Сибири, выполнен статистический анализ полученных данных и материалов наблюдений за уровнями подземных вод верхней гидродинамической зоны на участках вне явного антропогенного влияния. Установлено, что в регионе в последние десятилетия происходило статистически значимое увеличение подземной составляющей речного стока и уровней подземных вод. Увеличение подземного стока удовлетворительно объясняется смещением сроков установления снегового покрова и снеготаяния, снижением испарения с поверхности водосборов при уменьшении температур воздуха в летний период и увеличением температуры в остальные месяцы года даже при отсутствии изменений годового атмосферного увлажнения. Calculation of monthly average and mid-annual values of a ground flow in a taiga zone of Western Siberia is carried out. The statistical analysis of the received data and materials of supervision over levels of ground waters of the top hydrodynamical zone on sites outside of obvious anthropogenous influence is executed. In region last decades there was statistically significant increase in a underground component of a river drain and levels of ground waters. The increase in a ground flow well speaks displacement of terms of an establishment of a snow cover and snow melting, decrease in evaporation from a surface of river basins at reduction of temperatures of air during the summer period and increase in temperature in other months of year even at absence of changes of annual atmospheric humidifying

Ultrafast dynamics of melting and ablation at large laser intensities

This thesis contributes to the understanding of the ultrafast melting and ablation of solids irradiated at large laser intensities. Fundamental aspects of the ultrafast laser ablation of pure metals (Au, Al, Cu, Fe, W), such as laser-matter interaction, plasma formation, evaporation and melt dynamics have been matter of research. Melting and welding of technical borosilicate glass by high-repetition rate ultrafast laser radiation have been studied as well. Novel experimental techniques and tools have been developed and applied in order to enable investigations of laser induced transient phenomena on different time scales. Pump-probe imaging technique has been adopted featuring an extended temporal detection limit of approx. 2 microseconds and preserving a temporal resolution in the sub-picosecond range. A novel quantitative optical phase microscopy technique (TQPm) has been developed for time-resolved investigations of transient refractive index and morphology changes. For laser ablation of metals at large irradiation intensities, the temporal and spatial profiles of the adopted laser radiation have been examined. The heating effect of the radiation pedestals caused by amplified spontaneous emission has been estimated numerically resulting in a temperature increase by several hundreds of Kelvin, depending on material properties. Time-resolved shadowgraphy and quantitative measurements of the ablated volume in metals have been performed in different ambient conditions. In the adopted delay range, the observed ablation phenomena can be classified by at least four characteristic time regions, featuring the ejection of plasma and highly pressurized vapor, material vapor due to nucleation effects, liquid melt jets, and resolidification, respectively. Based on the experimental results of this work, a qualitative description for ablation of metals at large intensities is given, and important differences to the ablation at near-threshold intensities are specified. Particularly, phenomena concerned with overheating of material, e.g. phase explosion and “boiling crisis”, are assumed as the prevailing mechanisms of ablation. Melting of technical borosilicate glass by high-repetition rate ultrafast laser radiation has been studied dynamically by means of TQPm. The obtained results exhibit transient modifications of the refractive index which reflects either the ionization process or the material densification. An important application is established in terms of micro-welding of thin glass substrates with glass or silicon. By producing melt tracks in the interface between two substrates, reliable weld seams are generated in the micrometer regime

Ultrafast dynamics of melting and ablation at large laser intensities

This thesis contributes to the understanding of the ultrafast melting and ablation of solids irradiated at large laser intensities. Fundamental aspects of the ultrafast laser ablation of pure metals (Au, Al, Cu, Fe, W), such as laser-matter interaction, plasma formation, evaporation and melt dynamics have been matter of research. Melting and welding of technical borosilicate glass by high-repetition rate ultrafast laser radiation have been studied as well. Novel experimental techniques and tools have been developed and applied in order to enable investigations of laser induced transient phenomena on different time scales. Pump-probe imaging technique has been adopted featuring an extended temporal detection limit of approx. 2 microseconds and preserving a temporal resolution in the sub-picosecond range. A novel quantitative optical phase microscopy technique (TQPm) has been developed for time-resolved investigations of transient refractive index and morphology changes. For laser ablation of metals at large irradiation intensities, the temporal and spatial profiles of the adopted laser radiation have been examined. The heating effect of the radiation pedestals caused by amplified spontaneous emission has been estimated numerically resulting in a temperature increase by several hundreds of Kelvin, depending on material properties. Time-resolved shadowgraphy and quantitative measurements of the ablated volume in metals have been performed in different ambient conditions. In the adopted delay range, the observed ablation phenomena can be classified by at least four characteristic time regions, featuring the ejection of plasma and highly pressurized vapor, material vapor due to nucleation effects, liquid melt jets, and resolidification, respectively. Based on the experimental results of this work, a qualitative description for ablation of metals at large intensities is given, and important differences to the ablation at near-threshold intensities are specified. Particularly, phenomena concerned with overheating of material, e.g. phase explosion and “boiling crisis”, are assumed as the prevailing mechanisms of ablation. Melting of technical borosilicate glass by high-repetition rate ultrafast laser radiation has been studied dynamically by means of TQPm. The obtained results exhibit transient modifications of the refractive index which reflects either the ionization process or the material densification. An important application is established in terms of micro-welding of thin glass substrates with glass or silicon. By producing melt tracks in the interface between two substrates, reliable weld seams are generated in the micrometer regime

Material Response Of Semiconductors Irradiated With Ir Ultrashort Laser Pulses

We utilize near- and mid-IR ultrafast laser radiation to investigate the processing of crystalline silicon with different dopants. A numerical model is adopted to simulate the material response depending on the wavelength and the dopant concentration