Laser Cooled High-Power Fiber Amplifier

A theoretical model for laser cooled continuous-wave fiber amplifier is presented. The amplification process takes place in the Tm3+-doped core of the fluoride ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) glass fiber. The cooling process takes place in the Yb3+:ZBLAN fiber cladding. It is shown that for each value of the pump power and the amplified signal there is a distribution of the concentration of the Tm3+ along the length of the fiber amplifier, which provides its athermal operation. The influence of a small deviation in the value of the amplified signal on the temperature of the fiber with the fixed distribution of the Tm3+ions in the fiber cladding is investigated.Comment: 10 pages and 5 figure

Heat Evacuation from Active Raman Media Heat Evacuation from Active Raman Media Using Quasi-PT Symmetry Coupling

We propose to use frequency-selective quasi parity-time symmetry to reduce the heat generated by coherent anti-Stokes Raman scattering (CARS) reversed cycles in active Raman media with phase mismatch. This is accomplished using a coupled-waveguide structure, which includes the active Raman waveguide (RW), where the Stokes signal undergoes amplification via stimulated Stokes Raman scattering (SSRS), and a dissipative waveguide (DW), which is tuned to the anti-Stokes wavelength so as to evacuate the corresponding anti-Stokes photons from the RW by coupling. The DW introduces optical loss that partially offsets the growth of the anti-Stokes signal in the RW and hence suppress the reversed CARS cycles that would otherwise result into heat generation in the RW. It is shown that the frequency-selective quasi parity-time symmetry provided by the DW can reduce the heat in active Raman media by a very factor of up to five when the CARS phase mismatch is compensated for by the optimum level of coupling between the RW and the DW.Comment: 8 pages, 9 figure

Thermal transfer in a multilayer plate with source of metabolic heat

In this article heat transfer in a multi-layered plate (human skin and thermal insulation) with various boundary conditions is considered. This allows you to justify the choice of air temperature in the production premises

Raman fiber amplifier with integrated cooler

We present a new scheme for a laser cooled Raman optical fiber amplifier. The heat generated in the process of stimulated Raman scattering is compensated for with laser cooling provided by anti-Stokes fluorescence of ytterbium ions doped in the core of the fiber. The device is pumped with two pump sources. One of the pump sources provides Raman amplification of the signal and does not interact with the ytterbium ions in the core of the fiber. The second pump provides laser cooling of the fiber with anti-Stokes fluorescence of the Yb3+ ions. The proper arrangement of Yb3+distribution can provide athermal performance of the device.Comment: 13 pages, 6 figure

The Opportunity Analyses of Using Thermosyphons in Cooling Systems of Power Transformers on Thermal Stations

The opportunity analyses of using the thermosyphons as the main elements in the systems of thermal regime supplying has been conducted under the conditions of their usage in power transformers on thermal stations. Mathematical modeling of jointly proceeding processes of conduction, forced convection and phase transitions (evaporation and condensation) of coolant in the thermosyphon of rectangular cross section has been carried out. The problem of conjugated conductive-convective heat transfer was formulated in dimensionless variables "vorticity/stream function/temperature" and solved by finite difference method. The effect of the heat flux density supplied to the bottom cover of the thermosyphon from a transformer tank on the temperature drop in the steam channel was shown based on the analysis of numerical simulation results (temperature fields and velocities of steam). The parameters of energy-saturated equipment of thermal stations were found to be controlled by an intensification of heat removal from the top cover surface of the thermosyphon

School transition to the state-social management system based on the project approach application

The paper looks at the opportunities for the school transition to the state-social management system based on the project approach application. The principle methods and procedures for the project initiation are observed along with the project organization and planning, recourse provision and project monitoring. According to the author, the most effective form of initiating the management modernization project simultaneously involves the two participants: the internal (school management) and external (educational management organizations), provided that the external one sets the main requirements. Using the project approach allows the fast knowledge accumulation for further application. In this regard, it is more efficient than the program-targeted management requiring more time and effort for fulfilling the program. In author’s opinion, the project method can be extended to solving the problem situations. For example, its application is the most expedient in step-by-step implementation of the state-social management, given that not every school can restructure the existing management system by itself В статье представлены возможности перехода школ к государственно-общественному управлению на основе использования проектного подхода. Подробно рассмотрены основные методы и процедуры инициации проекта, организации и планирования проектных работ, их ресурсного обеспечения и мониторинга реализации проекта. Доказано, что наиболее эффективна форма, при которой инициация проекта модернизации управления осуществляется одновременно двумя субъектами: внутренним (руководством школы) и внешним (органами управления образованием), при условии, что внешний субъект задает основные требования. Использование проектного подхода позволяет достаточно быстро накопить знания, которые могут быть применены в последующем. В этом отношении он более эффективен, чем программно-целевое управление, при котором для выполнения программ требуется значительно больше времени и усилий. По мнению автора статьи, проектный метод работы следует распространять на решение новых проблемных ситуаций. Применение проектного подхода наиболее целесообразно, например, при поэтапном введении государственно-общественного управления, когда далеко не каждая школа готова самостоятельно перестраивать сложившуюся систему управлени

Extremely short-length surface plasmon resonance sensors

The impact of the system design on the control of coupling between planar waveguide modes and surface plasmon polaritons (SPP) is analyzed. We examine how the efficiency of the coupling can be enhanced by an appropriate dimensioning of a multi-layer device structure without using additional gratings. We demonstrate that by proper design the length of the device can be dramatically reduced through fabrication a surface plasmon resonance sensor based on the SPP-photon transformation rather then on SPP dissipation

Peculiarities of temperature fields formation in vapor channels of thermosyphons with heat carriers boiling at low temperatures

We conducted experiments on specially developed setup consisting of evaporation, transport and condensation parts. Heat was supplied to the evaporation part by the heating element which was supplied with voltage and alternating current from a single-phase transformer. Temperatures in the characteristic sections of each part were recorded by thermocouples. Junctions of thermocouples were mounted on the axis of symmetry in the liquid layer, at the lower boundary, in the middle part, and at the upper boundary of the vapor channel. To minimize the influence of the random factors (ambient air movement, operation of ventilation system, room temperature, etc.), we placed thermosyphon in a glass box. We used N-pentane as a heat carrier, and the filling ratio of the thermosyphon is equal to 4%