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981.
982.
983.
光纤频带宽、线径细、抗电磁干扰、抗腐蚀。近年来它在高能粒子物理、聚变研究、核爆和核动力学诊断等不利环境中的应用,引起了人们极大的关注。本文将扼要介绍采用光纤传输的快脉冲辐射诊断系统,并以核爆诊断为例说明这类系统的特点及与以往同轴电缆传输系统相比的优越性。 相似文献
984.
985.
一种新型光电式液位传感器 总被引:2,自引:0,他引:2
本文介绍一种新型光电式液位传感器的设计原理、光路的理论分析。该传感器具有液位测量准确、反应灵敏、防暴、使用寿命长等优点,是一种有很大实用价值的新型液位传感器。 相似文献
986.
The heavy ion beam (with fluence 3x108 ion/cm2) from a cyclotron has been used for irradiation of thin polyethylene naphthalate (PEN) films. Latent tracks in these polymeric films have been sensitized by UV radiation and then chemically etched in NaOH solution. The etching process parameters have been controlled by the electroconductivity method. After etching, parameters of samples have been examined by SEM and bubble point methods (Coulter® Porometer II instrument). Results have shown good quality of PEN track membranes with pore sizes in the range: 0.1 – 0.5 μm. The described procedure is known for thin polythylene terephthalate (PET) films. Taking into consideration that PEN films have got better mechanical, thermal, gas barrier as well as better chemical resistance properties in comparison with PET films, the possibility of application of such membranes is much wider. 相似文献
987.
Reflection of cold atoms from an array of current-carrying wires 总被引:1,自引:0,他引:1
D.C. Lau A.I. Sidorov G.I. Opat R.J. McLean W.J. Rowlands P. Hannaford 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(2):193-199
We report the realization of a new type of magnetostatic mirror for slowly moving atoms which comprises a planar array of
parallel wires alternately carrying electric current in opposite directions. One of the features of this atomic mirror is
that the magnetic field may be readily varied, switched or modulated by altering the current in the wires. Reflection signals
close to 100% at a pulsed current of 3 A are demonstrated for a beam of free-falling laser-cooled cesium atoms at normal incidence.
The current dependence of the reflection signals exhibits structure which is associated with the sequential onset of reflection
of cesium 62
S
1/2
, F=4 atoms in the m=+4, +3, +2 and +1 magnetic states. Measurements of the spatial distribution of the reflected atoms indicate the reflection
is predominantly specular at currents of 3 A.
Received: 31 August 1998 / Accepted: 6 October 1998 相似文献
988.
Y. Susuki 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(1):31-38
Neutral fractions of specularly reflected beams have been measured for the glancing-angle incidence of (0.2-0.5) MeV ions on a clean (001) surface of SnTe. The measured fractions have been compared with the results calculated by a classical
model for charge exchanges and by a model based on the first-order perturbation theory. The experimental and calculated results
have differed greatly. The disagreements are attributed to collisions with valence electrons on the surface. The electron
capture cross-sections of (0.2-0.5) MeV ions for valence electrons have been derived, based on the measured neutral fraction and distribution of valence electrons
for jellium background positive charges, and are found to be about ten times larger than those for the outermost electrons
of Sn and Te atoms calculated by the classical model.
Received: 23 October 1998 相似文献
989.
This paper focuses on measuring straightness of large-scale dimension by using laser diode fiber alignment, diffraction imaging technique and a CCD camera. In this method, we use a laser diode fiber alignment beam as the datum reference of straightness, deviation of the measured from this datum, can be detected by a CCD camera directly. Also a novel image processing algorithm is presented. The experiment result shows that the measurement range of L (m), the measurement accuracy of the system is 3+2.3×10-6L(\mm). 相似文献
990.
In order to study optical and electrical properties of (Pb1-xLax)TiO3 (PLT) films with varying La concentration, the PLT films were deposited by sol-gel process. X-ray diffraction revealed that a pseudocubic phase of the PLT film became dominant with increasing La concentration due to decrease of lattice constant of c-axis. Three-dimensional atomic force microscopy images showed that the grain size and root mean square surface roughness decreased by addition of La. The optical band gap of the PLT films became wider when Pb was substituted with La. The addition of La increased the transparency of the PbTiO3 film and shifted the threshold for initiation of absorption to shorter wavelength. Hysteresis loops of the PLT films showed that remanent polarization and coercive field decreased with increasing La concentration. In addition, we modified the surface of the PLT film with La concentration of 5% using a keV oxygen ion beam at different doses. The optical band gap of the PLT film was changed by the oxygen ion beam irradiation although the XRD patterns and the transmittance values were not significantly changed. In measuring AFM images of the surface of modified PLT film, significant changes of the grain shape and size were not found. Moreover, polarization and dielectric constant were not changed after oxygen ion irradiation. These results suggested that addition of La could affect the optical and electrical properties of the PbTiO3 and PLT films and that surface modification by oxygen ion beam modification with 1 keV energy can change the surface property but not bulk property. 相似文献