Laser interferometer for measuring the mass velocity of condensed substances in shock-wave experiments on the TWAC-ITEP proton-radiographic facility

The results of development of a laser interferometer designed for measuring the mass velocity of condensed substances in shock-wave experiments in the field of high-energy-density physics are presented. The interferometer is incorporated in the measuring complex of the TWAC-ITEP proton-radiographic facility. The developed laser system allows measurements of the velocity of free surfaces of samples in shock-wave experiments with an error no worse than 10 m/s for the entire range of velocities attained experimentally. The time resolution of measurements is limited by the response speed of the used PMTs and amounts to 2.5 ns. Combined investigations of shock-wave loading of metal targets and scabbing-fracture and jet-formation processes on free metal surfaces were performed by the proton-radiography and laser-interferometry methods.     

Laser flash method for measuring thermal conductivity of liquids-application to low thermal conductivity liquids

A laser flash method developed for the measurement of thermal conductivity of solids was applied to liquids of low thermal conductivity. The sample liquid was sandwiched in between a small thin metal disk and a sample holder. When the laser beam is absorbed in the front surface of the metal disk, the temperature of the disk quickly rises about 2 K and heat then flows downwards through the sample liquid as one-dimensional heat flow. The thermal conductivity of liquid can be obtained from the temperature fall of the disk without employing any reference materials and also without measuring the thickness of the sample liquid layer. Thermal conductivities of water and toluene near room temperature were measured by this method with a mean deviation of 2.6%. This laser flash method may be applied to the measurement of the thermal conductivity of liquids such as molten salts at elevated temperatures.     

A convenient method for the measurement of species composition from an intense neutral beam

We present a method to infer the approximate species mixture of neutral beam sources which accelerate positive hydrogen ions. An idealized neutral beam is specified by the accelerating voltage, the neutralizer thickness (molecules of hydrogen per cm2), and the currents of extracted H+, H2+, and H3+. These currents define two independent ratios which lie within a narrow parameter region and which can be determined by two independent measurements downstream from the source. The two suitable parameters are (1) the ratio of neutral beam to total beam power; and (2) the ratio of hydrogen produced by the neutral beam in the target volume to the hydrogen produced by the total beam. We give experimental results from the 10 x 10-cm2 120-KeV test stand at the Lawrence Berkeley Laboratory.     

New method for measuring the thermal conductivity

A new experimental method is presented for measuring the thermal conductivity as a function of temperature. The basic innovation lies in extracting from the measured temperature profile of a sample in vacuo, the thermal conductivity of each individual cross-sectional sample element. The estimated experimental error is +/-1%. Not only is high accuracy achieved, but also a self-checking procedure offers the possibility of avoiding systematic errors. Measurements on two samples of type 304 stainless steel are presented. Three independent sets of measurements give consistent values for the thermal conductivity to well within the estimated error of +/-1%.     

Dynamic characteristics of rotating pretwisted clamped-clamped beam under thermal stress

Effects of thermal stress on the vibration characteristics, buckling limit and critical speed of a rotating pretwisted beam clamped to rigid hub at a stagger angle were investigated. By considering the work done by thermal stress, the thermal influence on stiffness matrix was introduced in the dynamic model. The motion equations were derived based on Lagrange equation by employing three pure Cartesian deformation variables combined with nonlinear von Karman strain formula. Numerical investigations studied the modal characteristics of the beam. Numerical results calculated from a commercial finite element code and obtained with the present modeling method were in good agreement with the previous results reported in the literature. The combined softening effects due to the thermal stress and the rotation motion were observed. Furthermore, it is shown that the inclusion of thermal stress is necessary for blades operating under a high temperature field. Buckling thermal loads and the critical rotating speed were calculated through solving the corresponding nonlinear equations numerically, and some pertinent conclusions are outlined. It is also found that the peak value position of the first mode shape approaches to the tip of blade with the increment of rotating speed and hub radius. However, the variation in the environment temperature causes only a slight alteration in the mode shape.     

Measurements of the profile of an intense electron beam

Methods for measuring the profiles of high-power electron beams by using a thin tungsten wire moved transversely to the beam have been developed. In one method, the electron current intercepted by the wire is measured and the beam profile is determined from a solution to the Abel equation under the assumption of axial beam symmetry. The second method is based on the detection of the local radiation emitted by the wire being heated by the beam to 1700–2200 K. The wire is additionally heated by an electric current in order to improve the sensitivity and spatial resolution. The measured beam current density is ～5–50 A/cm², and the resolution is ～0.1 cm.     

Improved technique for measuring intense pulsed ion beams by the nuclear activation method

A technique capable of measuring very high ion fluences by the nuclear activation method is described. The method eliminates the adverse effects of target blowoff by placing the target in a specially designed enclosure.     

An instrument for measuring thermal characteristics of metals and alloys

An all-soldered instrument capable of measuring the density, surface tension, electron work function for metals or alloys, and wetting of solid surfaces under high static vacuum conditions has been designed and tested. Measurements of thermal characteristics of lithium samples have demonstrated a high reliability of the instrument. Original Russian Text ? B.B. Alchagirov, L.Kh. Afaunova, F.F. Dyshekova, T.M. Taova, R.Kh. Arkhestov, A.G. Mozgovoi, Z.A. Kokov, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 3, pp. 148–151.     

New device and method for measuring thermal conductivity of thin-films

Thermal sensitive paints (TSPs) are used for global nonintrusive detection of boundary layer transition in flow over the surface of wind tunnel research models. Since the transition is a transient process, the TSP should have a fast response characteristic. A low paint thermal conductivity is required for fast response. A thin-film thermal conductivity meter (TFTCM) was designed and built to measure thermal conductivity of the TSPs, which are typically between 50 and 150 microm thick. In this paper, the design and operating features of the TFTCM are described. Measurement of the thermal conductivity with this TFTCM of three standard thin-film low conductivity specimens, Kapton, Teflon, and Borofloat glass, showed good agreement with the manufacturer quoted values, thus validating the instrument and the procedure. Consistently repeatable values for thermal conductivity (k=0.41 +/- 0.02 W/m K) were also obtained for the TSP specimen (TSB-B, 75 microm) tested.     

柴油机热平衡冷却液流量测量方法

为克服工程机械柴油机热平衡现场实验中难以安装冷却液流量计造成的热平衡动态分析困难,设计了一种通过测定柴油机散热器进出水口压力差来确定冷却液流量的间接测定方法.此方法根据柴油机台架热平衡实验中的流量压降关系标定柴油机体内流道阻力特性,并在现场实验中测量额定转速下柴油机进出水口压力差,结合离心泵外特性曲线排除散热器内流道阻力影响,实现现场实验时流量值的确定.该方法可作为柴油机热平衡现场实验时的流量估算.     

A simple method for measuring time-of-flight spectra of a gas-dynamic molecular beam

A simple and sensitive method is proposed for studying gas-dynamic seeded beams containing molecules of some salts of alkali metals and thallium with ionic bonds. This method is based on the use of dissociation of these molecules induced by collisions with xenon. A secondary electron multiplier serves as the detector of a molecular beam. The proposed method has been tested on a seeded gas-dynamic beam of CsCl molecules at a pressure of the carrier gas (hydrogen) of 1–5 atm and with energies no higher than 20 eV. This method has shown high accuracy and reproducibility of results.     

A nondestructive method for measuring thermal parameters of hermetically sealed electron devices

The nonrestrictive method described is intended for measuring the quantity of heat coming from the surroundings into the working volume of the hermetically sealed device with a thermoelectric cooler. The method is based on the dependence of the thermal emf that appears across the thermopile leads of the thermoelectric cooler in the stationary operation mode on the thermal load on the heat-absorbing surface.     

Scanning with parallel transfer of an electron beam for a transverse profile monitor of an intense ion bunch

A method for fast parallel scanning of a low-energy electron beam (scan amplitude, ± 4 cm; scan time, 10 ns; beam energy, 60 keV) is described. Results of application of this method to nondestructive diagnostics of the proton bunch are presented.     

Technique for measuring the beam shape of pulsed lasers

A simple technique for the measurement of the beam shape parameters of pulsed lasers, with just a single pulse of the laser is described. It involves the use of several beam dividers inclined at very small angles to the beam axis, reflecting the beam back to a screen or a phosphor placed near the exit of the laser. The reflected images are then photographed by a camera to yield the beam parameters.     

Realization of the longitudinal heat flow method for measuring thermal conductivity of solids at high temperatures

An experimental plant intended for high-temperature investigations of the thermal conductivity of structural materials is described. Results of investigations of the thermal conductivity of 12X18H10T stain-less steel in a 480- to 1200-K temperature range are given.     

A setup for measuring the refractive index of a plane-parallel ceramic plate using the optical beam shift method

A setup for measuring the refractive indices of transparent solid samples of optical ceramics using shifts of a beam by a plane-parallel plate in a wavelength range of 400–1200 nm was developed. The minimum cross-sectional sizes of the investigated objects are 5–12 mm, and their thicknesses are 0.3–1.0 mm. A standard sample and a precise system for forming and recording optical signals equipped with a stepping motor with a step discreteness of <1 μm were used to improve the measurement accuracy of the refractive index. The cross-sectional size of the measuring beam is ?1 mm. The accuracy in determining the refractive index is ±0.004.     

随机道路谱作用下的汽车响应特性

针对驱动桥壳在随机道路谱作用下的响应特性问题,建立了汽车振动的7自由度动力学方程,应用随机振动理论求解出了汽车在路面不平度下的频率响应(FR),利用Matlab得到了不同速度下的后桥垂向振动加速度功率谱密度(PSD)。研究结果表明该随机道路谱作用下的汽车响应特性研究对驱动桥的动态设计具有一定的参考和应用价值。     

An optical pump-probe technique for measuring the thermal conductivity of liquids

We present a pump-probe optical technique for measuring the thermal conductivity of liquids. The technique uses a reflective geometry which does not depend on the optical properties of the liquid and requires as little as a single droplet to produce a result. An analytical solution is given for bidirectional heat flow in layered media, including the effects of radial heat flow from coaxial Gaussian laser spots, thermal interface resistances, and the accumulation of multiple laser pulses. In addition, several experimental improvements over previous pump-probe configurations are described, resulting in an improved signal to noise ratio and smaller errors at long stage delay times. The technique is applied to a range of liquids and solids. Results are in good agreement with literature values.     

A unit for measuring the effective thermal conductivity of thin-layer materials

An experimental setup for determination of the absolute values of thermal-conductivity and heattransfer coefficients of thin-layer spacers at room temperature and higher is described. The experimental data processing procedure is given.     

Turbidimetric method for measuring the parameters of submicron aerosols

A new turbidimetric method for determining the parameters of submicron aerosols was developed and implemented in hardware using a wide range of probe radiation wavelengths and high-speed video recording. The particle size distribution function is found using an original algorithm for solving the inverse problem of the optics of aerosols based on a direct search computational procedure..