An Investigation of the Influence of the Plasma Current on the Ion Heat Transport in the Globus-M Spherical Tokamak

Experiments intended to study the dependence of the ion temperature on the plasma current were carried out on the Globus-M spherical tokamak. The ion temperature was measured at a few spatial points with the help of charge exchange spectroscopy and a charge exchange atom analyzer. On the basis of the experimental data, modeling with the use of the ASTRA numerical code was carried out and the thermal diffusivities for the ion plasma component were determined. The calculation results show that the ion behavior is similar to neoclassical.     

Density Gradient Evolution Effect on Ion Cyclotron Waves Excitation in TUMAN-3M Tokamak Ohmic Discharges

Technical Physics Letters - In TUMAN-3M tokamak ohmic hydrogen and deuterium discharges oscillations with ion cyclotron (IC) frequency were detected. Fast magnetic probes poloidal array in TUMAN-3M...     

Observation of geodesic acoustic modes in the Globus-M spherical Tokamak

The first results of an investigation of geodesic acoustic modes (GAMs) in the Globus-M spherical tokamak are presented. The experiments were performed using Doppler reflectometry. The conditions of the appearance of GAMs, the nature of their development, and their radial localization have been studied. The obtained data are compared to experimental results obtained in tokamaks with large aspect ratios.     

The Effect of Low-Frequency Magnetohydrodynamic Modes on the Development of Filaments in the Globus-M Tokamak

Technical Physics Letters - Experimental data are presented that indicate the effect of the magnetohydrodynamic tearing mode in the Globus-M spherical tokamak on the occurrence of filamentary...     

Particle Image Velocimetry Studies of Counterflow Heat Transport in Superfluid Helium II

Heat is transported in helium II by a mechanism known as thermal counterflow where the liquid behaves as if it consists of two fluid components: the viscous normal fluid that carries the entropy and the inviscid superfluid that flows in opposition to conserve mass and momentum. Although the two fluid model has been successful at interpreting a number of unique transport processes in helium II, only recently has there been a significant effort to actually observe the associated fluid component motion. We have previously shown that Particle Image Velocimetry (PIV) can be used to visualize the motion of micron scale particles in helium II in response to thermal counterflow. These studies have led to some exceptional observations. The present paper summarizes our recent PIV experimental results on counterflow in helium II including the observed flow patterns around a cylinder and through a rectangular channel with backward facing step change in cross section, configurations which have been studied extensively in classical fluid mechanics. In addition to contributing to the fundamental understanding of helium II turbulence, as is discussed in the last section of the article, we show how this work also has a potential application in micron-scale particle classification and separation.     

气－液两相界面上的热质传输过程

根据气－液相界面上的不平衡效应，分析了鼓泡蒸发冷却循环水的原理及实现的条件。也阐述了确定装置主要流体力学控制参数的方法。     

Accounting for Energy Accommodation in Calculating the Heat Flux from a Spherical Particle in a Diatomic Gas

The problem of calculation of the heat flux from a uniformly heated spherical particle in a diatomic gas is considered with account for the energy-accommodation effect. The results of numerical calculations for the analog of the BGK collision-integral model are presented.     

The Inclusion of Energy Accommodation in Calculating the Heat Flux from a Spherical Particle in a Polyatomic Gas

The problem on the calculation of the heat flux from a uniformly heated spherical particle in a polyatomic gas is treated with due regard for the effect of energy accommodation. The results of numerical calculations are given for an analog of the Bhatnagar–Gross–Krook model of the collision integral. The distributions of temperature and energy over degrees of freedom are analyzed for the case of their separate excitation.     

On Allowance for Energy Accommodation in Calculating the Heat Flux from a Spherical Particle at Arbitrary Knudsen Numbers

The present paper considers the problem on the calculation of the heat flux from a uniformly heated spherical particle at arbitrary values of the Knudsen number with allowance for the energyaccommodation effect. The results of numerical calculations of the BGK model of the collision integral are presented.     

Modeling of Heat and Aerosol Discharges of Power Complexes into the Surrounding Medium

The sources of possible technogenic pollution of the atmosphere near power units are discussed. A procedure for evaluating the interaction of coolingtower plumes with technogenic discharges of power units and with other pollutants of the atmosphere is presented. Results of a series of computational experiments as applied to an analysis of the action of the discharges of cooling towers on the aerosol discharges of ventilation systems of nuclear power plants (NPPs) are reported.     

Unsteady Heat Transfer in HeII in Cylindrical and Spherical Geometries

The problem of evolution of strong heat pulses in superfluid helium interacting with quantum vortices induced by these pulses is investigated numerically on the basis of equations of hydrodynamics of superfluid turbulence. The “discontinuity decay” method (Godunov method) is used for the calculations. In order to study nonlinear effects, the initial equations are expanded to the second order in the amplitudes of pulses. The influence of the main flow parameters—heat flux and rest time—on temperature evolution is reported. The numerical investigations are carried out at the bath temperature of 1.4 K. The obtained results are compared with experimental data.      

Solution of the Boltzmann Kinetic Equation in the Problem on Calculation of Heat Flux from a Spherical Particle at Arbitrary Values of Knudsen Number

The problem on calculation of the heat flux from a uniformly heated spherical particle in an arbitrary range of the Knudsen number is solved. Numerical calculations are performed for a model of molecules interacting as elastic hard spheres under the condition that their reflection from the surface of the particle is purely diffuse.     

Comparison of the IOFFE neutral particle analyser with the Princeton analyser on the Mega Amp Spherical Tokamak

Charge exchange-neutral particle analysis (CX-NPA) will be applied for determining the ion temperature in the stellarator Wendelstein 7-X (W7-X), which is under construction, now, at the Max-Planck-Institute of Plasma Physics, Greifswald, Germany. Three ACORD-type analyser and one compact analyser (CNPA) are foreseen for the active NPA diagnostics at W7-X, i.e. NPA in combination with a 60 keV neutral beam injector, thus enabling locally resolved CX-NPA measurements. For an intermediate period the CNPA is now installed on the Mega Amp Spherical Tokamak (MAST) in Culham Science Centre, UK.The arrangement of the CNPA on MAST and results of energy spectra of plasma ions in MAST are presented. They are in a good agreement with measurements by the Princeton particle analyser.     

Close Approach of a Spherical Particle and a Quantised Vortex in Helium II

To interpret the results of recent experiments which used the Particle Image Velocimetry (PIV) method it is necessary to understand the interaction of the particles with the quantised vortices. We present numerical calculations of the close approach of a small spherical particle to a vortex line. The collision time scale compares well with approximate analytical results.     

Gas Flow and Particle Transport and Deposition in a Pilot-Scale Furnace

The present work describes a computer simulation study of gas flow and particle transport and deposition in a pilot-scale furnace with cooling system. The Gambit code is used to generate the geometry and the computational grid. An unstructured mesh is generated for the pilot-scale boiler. The FLUENT code is used for evaluating the gas mean velocity, turbulence fluctuation energy, and mean pressure, as well as temperature fields and chemical species concentrations. The particle equation of motion includes the nonlinear drag, gravity, Brownian, lift, and thermophoretic forces. The gas velocity and thermal conditions in the furnace are studied. Ensembles of particle trajectories are generated and statistically analyzed. Particle deposition rates on different walls are evaluated, and the effect of particle size is studied.     

用恒热流法测定多孔介质的热质迁移特性参数

设计了一种测定多孔介质热质迁移特性的实验装置。通过测定该装置中多孔介质的局部温含量和温度，结合恒热流下一维半无限大多孔介质热质迁移微分方程的解，得到了石英砂、玻璃珠等多孔介质的质扩散系数、热质扩散系数、名义热扩散系数、名义导热系数等热质迁移特性参数以及这些参数随湿含量、温度的变化。此外，还讨论了加热功率、初始湿含量等因素对测量的影响。     

The Growth and Stability of Vapor Film on the Surface of a Hot Spherical Particle

The problem on the thermal interaction between a hot thermal particle and ambient water is treated. The stability of a growing vapor film to small perturbations of its spherical shape is investigated.     

两相体系中第二相颗粒粗化的研究进展

综述了近年来两相体系中第二相颗粒粗化的研究进展,LSW理论能对颗粒的Ostwald熟化过程进行定量,并且第二相体积分数、弹性应力以及颗粒形状和合金元素等对Ostwald熟化过程有影响.LSW理论仍来源于驱动力的分析和基本方程的推导.对于纳米两相体系,其第二相颗粒的粗化仍满足经典的Ostwald熟化理论--LSW理论.纳米颗粒粗化行为的理论研究与钢铁生产紧密相联,钢铁产品的性能提高与其中夹杂物的尺寸控制有关,第二相Ostwald熟化理论将能有效应用于钢铁夹杂物纳米尺度的控制.     

Self-Organized Heat Transport Near the Superfluid Transition in 4He

Heat transport through a column of superfluid ⁴ He has been observed experimentally to self-organize, resulting in a thermal gradient that exactly matches the gradient in the superfluid transition temperature across the column, leaving the entire sample at a constant distance from the superfluid critical point¹. We describe a new experiment that is designed to accomplish three objectives: 1) search for the upper critical heat flux above which self-organized heat transport can no longer occur, 2) measure the heat capacity of the self-organized heat transport state, and 3) test recent theoretical predictions^2,3 of the microscopic mechanism that is responsible for this self-organization.     

Berry Phase and Topological Spin Transport in the Chiral d-Density Wave State

In this paper we demonstrate the possibility of dissipationless spin transport in the chiral d-density wave state, by the sole application of a uniform Zeeman field gradient. The occurrence of these spontaneous spin currents is attributed to the parity (℘) and time-reversal ( ) violation induced by the density wave order parameter. We calculate the spin Hall conductance and reveal its intimate relation to the Berry phase which is generated when the Zeeman field is applied adiabatically. Finally, we demonstrate that in the zero temperature and doping case, the spin Hall conductance is quantized as it becomes a topological invariant.