HT20—40铸铁中碳的光电光谱分析

本文主要论述HT20-40铸铁中碳的光电光谱分析。由于薄片样急冷快,白口化好,这样解决了铸铁样品难以白口化的问题。为了加工薄片样,设计了磁钢磨具。解决了加工薄片样非常困难的问题。实践证明,只要严格控制铸铁样分析条件,碳的光电光谱分析结果完全达到了要求。     

温度对应变式位移传感系统灵敏系数的影响

应变式位移传感系统的工作原理是基于电阻应变效应,该系统具有精度高﹑稳定性好等优点,但温度尤其是极端低温环境将影响该系统的灵敏系数,进而影响其测量精度.本文介绍了一种可用于低温环境的应变式位移传感系统,理论分析和实验研究了温度对该系统灵敏系数的影响,研究结果为其在低温环境中的应用提供了一定基础。     

Total cross sections for photoabsorption on light nuclei in the energy range 600–1500 MeV

Experimental data of the GRAAL Collaboration on the total cross sections for photoabsorption on deuterium and carbon targets at gamma-ray energies in the range between 600 and 1500 MeV are presented. The experiment was performed in a beam of photons obtained by the method of the Compton backscattering of laser photons at the electron storage ring of the European Synchrotron Radiation Facility (ESRF, Grenoble, France) by using a wide-aperture detector covering a solid angle close to 4π. The total photoabsorption cross sections were determined by two independent methods: by subtracting the emptytarget background and by summing partial cross sections for meson photoproduction. The total cross sections for photoabsorption on quasifree protons and neutrons are shown to agree both in magnitude and in shape within a 5% precision of the measurements. In contrast to data previously available in the literature, both cross sections show distinctly the F ₁₅(1680) resonance at a photon energy of about 1 GeV. Data obtained in the present experiment for the cross sections for photoabsorption on a free and a bound nucleon are compared. This comparison reveals a substantial role of two-nucleon correlations in estimating the nuclear-medium effect on meson photoproduction.     

Double excitations of helium in weak static electric fields

A dramatic electric field dependence has been observed in the fluorescence yield spectrum of the doubly excited states in helium, where a rich phenomenology is encountered below the threshold. Fluorescence yields of certain states can be tuned to zero, while other dipole-forbidden states are significantly enhanced, for fields much weaker than 1 kV/cm. Using an R-matrix multichannel quantum defect theory, spherical-to-parabolic frame transformation method, we are able to reproduce the main features of the observed spectrum, and we discuss the qualitative behavior in terms of weak electric field mixing.     

Runaway Electron Measurements in the EAST Tokamak

An experimental study of runaway electrons in the EAST tokamak has been performed by a recently developed multi‐channel hard x‐ray diagnostics based on NaI(TL) scintillator detectors. It is found that in the current quench phase, the inductive loop voltage plays an important role in the generation of runaway electrons. And the avalanche mechanism was the main mechanism for runaway electrons after the disruptions. The distribution and transportation of runaway electrons were also investigated by multi‐channel hard x‐ray diagnostics. It is also found that the intensity of runaway electrons emission in the core plasma was much higher than those in the downside of the cross‐section, while the emission intensity of runaway electrons in the core plasma was almost the same. Calculated shrinking coefficient of runaway electrons emission after the plasma disruption was about 26 m/s according to the experimental data (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Evolution of filament structures during edge-localized modes in the MAST Tokamak

Edge-localized modes (ELMs) are repetitive instabilities that occur in the outer region of tokamak plasmas. This Letter provides new information on and the implications of the evolution of the filament structures observed during ELMs in the MAST tokamak. The filaments exist for the time over which particles are being released into the scrape off layer. They start off at the plasma edge rotating at the velocity of the pedestal, and then decelerate toroidally and accelerate radially outwards. As the filaments propagate radially they remain aligned with the local magnetic field line.     

Pairs of F centres and CN− molecules in KCl: An ENDOR analysis

Abstract

Pair defects consisting of F centres and CN^? molecules as substitutional impurity anions (F_H(CN^?) centres) exhibit a strong coupling between the F centres and the CN^? molecules. This leads to an optical pumping of the CN^? vibrations via the F centre absorption band. We performed an Electron Nuclear Double Resonance (ENDOR) investigation in order to analyse the microscopic structure of these aggregate centres. The CN^? molecule occupies a [110] nearest anion position with respect to the F centre in two dynamic dipole orientations even at low temperature.     

Endor for characterizing transition metal centres in LiNbO3

Abstract

ENDOR investigations show that in nearly stoichiometric LiNbO₃ Mn²⁺ substitutes for Li with a Li vacancy in the first Li shell for most centres. In heavily Mg codoped LiNbO₃ the Cr³⁺ dopant, characterized by a new isotropic ESR signal, is shown to substitute for Nb. Information on local disorder is obtained.     

Transition between internal transport barriers with different temperature-profile curvatures in JT-60U Tokamak plasmas

A spontaneous transition phenomena between two states of a plasma with an internal transport barrier (ITB) is observed in the steady-state phase of the magnetic shear in the negative magnetic shear plasma in the JT-60U tokamak. These two ITB states are characterized by different profiles of the second radial derivative of the ion temperature inside the ITB region (one has a weak concave shape and the other has a strong convex shape) and by different degrees of sharpness of the interfaces between the L mode and the ITB region, which is determined by the turbulence penetration into the ITB region.     

HT-7电子加热实验的软X射线能谱诊断

介绍了HT-7装置上软X射线能谱诊断系统,用软X射线能谱对HT-7托卡马克上电子温度进行了测量。在离子伯恩斯坦波和低杂波协同实验中,观察到了对等离子体的较好的加热效果。