Расчеты напряженно-деформированного состояния бетонной плотины Богучанской ГЭС с применением разных моделей бетона и скального основания

The 2-D stress-strain state analyses of Boguchansk concrete dam was performed using ADINA program with various models of concrete and rock foundation: elastic, ideally elasto-plastic with Mohr-Column criterion and nonlinear brittle models. The main properties of the nonlinear brittle model with strength softening of concrete and rock foundation were considered. The stress-strain state of dam sections under actions of hydrostatic and uplift pressures was analyzed and assessed as a favorable, but severe cold winter temperatures can transfer the dam state into unfavorable.Представлены результаты расчетов напряженно-деформированного состояния (НДС) бетонной плотины строящейся Богучанской ГЭС, выполненные с помощью программы ADINA с использованием разных моделей бетона и скального основания: упругой, идеально упруго-пластической Мора-Кулона и нелинейной хрупкой. Рассмотрены основные свойства нелинейной хрупкой модели с учетом разупрочнения бетона и скального основания. Напряженно-деформированное состояние плотины при действии статически нагрузок оценивается как благоприятное, но низкие зимние наружные температуры могут перевести это состояние в неблагоприятное

Generation of Collisionless Shocks by Laser-Plasma Piston in Magnetised Background: Experiment “BUW”

Theoretical basis and main results of the first successful large-scale, Laser-Plasma experiment “BUW”, on generation of Collisionless Shock Wave in magnetised Background Plasma, are presented. Our classic approach is based on the action of so called Magnetic Laminar Mechanism (or Larmor coupling) for collisionless interaction between interpenetrating super-Alfvenic plasma flows of Laser-Plasma and Background in transverse magnetic field

An exact solution of the moving boundary problem for the relativistic plasma expansion in a dipole magnetic field

An exact analytic solution is obtained for a uniformly expanding, neutral, highly conducting plasma sphere in an ambient dipole magnetic field with an arbitrary orientation of the dipole moment in the space. Based on this solution the electrodynamical aspects related to the emission and transformation of energy have been considered. In order to highlight the effect of the orientation of the dipole moment in the space we compare our results obtained for parallel orientation with those for transversal orientation. The results obtained can be used to treat qualitatively experimental and simulation data, and several phenomena of astrophysical and laboratory significance.Comment: 7 pages, 2 figures. arXiv admin note: substantial text overlap with arXiv:physics/060323

GENERATION OF QUASI-PERPENDIQULARE COLLISIONLESS SHOCKS BY LASER-PRODUCED PLASMA TO SIMULATE THE EFFECTS OF SUPER-COMPRESSION OF THE EARTH MAGNETOSPHERE

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On the possibility for laboratory simulation of generation of Alfvén disturbances in magnetic tubes in the solar atmosphere

The paper deals with generation of Alfvén plasma disturbances in magnetic flux tubes through exploding laser plasma in magnetized background plasma. Processes with similar effect of excitation of torsion-type waves seem to provide energy transfer from the solar photosphere to the corona. The studies were carried out at experimental stand KI-1 representing a high-vacuum chamber 1.2 m in diameter, 5 m in length, external magnetic field up to 500 G along the chamber axis, and up to 2·10–6 Torr pressure in operating mode. Laser plasma was produced when focusing the CO2 laser pulse on a flat polyethylene target, and then the laser plasma propagated in θ-pinch background hydrogen (or helium) plasma. As a result, the magnetic flux tube 15–20 cm in radius was experimentally simulated along the chamber axis and the external magnetic field direction. Also, the plasma density distribution in the tube was measured. Alfvén wave propagation along the magnetic field was registered from disturbance of the magnetic field transverse component Bφ and field-aligned current Jz. The disturbances propagate at a near-Alfvén velocity 70–90 km/s and they are of left-hand circular polarization of the transverse component of magnetic field. Presumably, the Alfvén wave is generated by the magnetic laminar mechanism of collisionless interaction between laser plasma cloud and background. A right-hand polarized high-frequency whistler predictor was registered which propagated before the Alfvén wave at a velocity of 300 km/s. The polarization direction changed with the Alfvén wave coming. Features of a slow magnetosonic wave as a sudden change in background plasma concentration along with simultaneous displacement of the external magnetic field were found. The disturbance propagates at ~20–30 km/s velocity, which is close to that of ion sound at low plasma beta value. From preliminary estimates, the disturbance transfers about 10 % of the original energy of laser plasma

Charge-transfer pumping of O+5 ions with emission at 51.2 nm

A charge transfer pumping as a possible tool for lasing in XUV is investigated in the Institute of Laser Physics, Novosibirsk. A new scheme based on the laser-produced plasma colliding with the laser-evaporated gas was previously proposed and tested. It showed that lasing at 51.2 nm can be achieved on the 4-3 transition of Li-like O+5 ion. Preliminary results on the enhanced emission at 50 nm and on the specifics of charge transfer reaction [MATH] are reported

GENERATION OF QUASI-PERPENDIQULARE COLLISIONLESS SHOCKS BY LASER-PRODUCED PLASMA TO SIMULATE THE EFFECTS OF SUPER-COMPRESSION OF THE EARTH MAGNETOSPHERE

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