材料渗透系数的测定

研制了一套渗透系数测定装置。用它可以测量包活渗透系数极低和极高材料在内的各种固体室温和低温下的渗透系数。介绍了结构原理、操作程序以及对一些试样的测量结果。     

基于光腔衰荡光谱技术的痕量甲烷检测

为精确测量氮气中痕量甲烷(CH_4)浓度,设计并搭建了基于三角环形腔的连续波光腔衰荡光谱(CW-CRDS)测量装置。衰荡腔为自主加工设计,由一片曲率半径为1 m直径为25 mm的凹面镜和两片直径为12.7 mm的平面镜围成,腔内光路总长为410 mm,腔体材料为殷钢。首先,对系统的基线损耗进行了测量,随后利用氮气作为混合气配置了五种不同浓度的CH_4与N_2的混合气,利用CH_4在1 653.7 nm的吸收峰(CH_42ν3带R5支)对气体进行检测,并根据吸收谱线特性,利用洛伦兹线型函数通过最小二乘法拟合出衰荡时间常数τ并计算CH_4浓度,所搭建装置对甲烷浓度(体积分数)的检测灵敏度可达54×10~(-9)(五点四亿分之一)。最后对浓度为510×10~(-9)(五千一百万分之一)的CH_4在6 046.7～6 047.2cm~(-1)范围内的吸收光谱进行了测量,并将测得数据依照腔自由光谱范围(FSR)分组后分别拟合出τ和吸收系数,将所得CH_4吸收系数与数据库中数据相比,其最大误差低于1.2×10~(-9) cm~(-1),最高精度达8.8×10~(-11) cm~(-1)。     

人眼波前像差的动态特性研究

人眼波前像差随时间涨落会引起人眼光学性能和视觉功能的改变.采用改进的HartmannShack波前传感器人眼像差仪对10只屈光度为0D~-5.0D、直径为3mm和6mm的人眼瞳孔的波前像差进行测量,其中每只人眼在5s内连续测量125次,测量频率为25Hz.为确定测量过程中是否引入人为像差,对人造眼3mm和6mm瞳孔的动态波前像差进行测量比对.结果表明:所测量的10只人眼3mm和6mm瞳孔总的Zernike波前像差均方根涨落幅度的平均值分别为0.087μm和0.105μm,均大于Marechal衍射极限;Zernike第3阶到第7阶波前像差均方根涨落幅度随像差阶数的递增而下降,涨落幅度为0.06~0.02μm;人眼波前像差的涨落频率达6Hz.     

玻璃微球壁厚和预充气工艺对气体渗透性能的影响

 以空心玻璃微球为研究对象，利用高压充气系统充气，测量了不同条件下玻璃微球对氘气在室温条件下的气体渗透系数。研究结果表明：微球的壁厚对气体渗透系数影响较大，2 mm以上厚壁球的气体渗透系数约5.0×10^-22 mol·m^-1·s^-1·Pa^-1，而壁厚小于1 mm时，渗透系数约1.56×10^-20 mol·m^-1·s^-1·Pa^-1，两者相差30倍。预充气挑选工艺对微球的气体渗透系数也产生一定影响，对于薄壁空心玻璃微球一次充放气气体渗透系数增加约50％，两次充放气则增大一倍左右。对上述影响因素进行了初步的探讨，气体渗透系数改变的主要原因是玻璃微球表面的结构裂纹、空位和缺陷。     

掺还原铁粉混凝土板反射和透射性能

通过控制混凝土板的厚度、混凝土板中还原铁粉掺量、在混凝土板中加钢丝网,研究混凝土板对电磁波的反射和透射性能。反射率测量采用弓形架测试方法,透射衰减测量采用两端口测试方法。混凝土板对电磁波的反射率测试频段为2~18GHz,透射衰减测试频段为12~18GHz。不同的混凝土板对电磁波的反射率在-5dB左右。40mm厚的混凝土板中还原铁粉的掺量超过200kg/m3时,电磁波的透射衰减量可达到-50dB以上。通过分析实验结果,发现混凝土板的厚度、混凝土板中还原铁粉掺量和钢丝网对反射率大小影响较小,对透射衰减量影响较大。     

利用针缝法测量强流栅控脉冲电子枪束流发射度

采用单缝单针法测量电子枪束流的发射度。用可移动的宽0.1mm单缝取样,与缝平行的直径为0.1mm匀速运动的探针接收穿过狭缝的束流。 缝、针距离为59mm,角分辨率为3.4mrad,系统最大接收度为0.64cm·rad。缝、针间设有平行度调节装置,提高了测量精度;狭缝板设有水冷结构,可承受较大的束流功率,采用良好的屏蔽及合理的二次电子抑制结构,清晰地测出了10~(-10)A量级的弱信号电流。所测相图的相对误差约为8％。利用该装置方便地测得了电子枪高压、栅控脉冲电压、阴极温度、脉冲流强等不同条件下的发射度变化。     

光纤传感器测量固体材料线胀系数实验的改进

对反射式光纤传感器测量固体材料线胀系数实验进行了改进.光纤探头采用多光纤同轴发射/接收,提高了光纤传感器的灵敏度,低压硅胶板的加热方式改变了传统的加热方式,提高了温度测量的准确度,同时还改进了材料的加热方式,并将传感器输出特性的线性区间与材料热膨胀时的线性变化直接对比进行数据处理.改进后的实验装置简单且便于操作,可测量长度为200mm的样品,测得有机玻璃和黄铜的线膨胀系数分别为131.4×10-6/℃和18.35×10-6/℃,实验结果的相对偏差约为1%.     

用钮扣电极测量强流直线感应加速器束流位置

 介绍了钮扣电极测量强脉冲束流位置的基本原理，以及针对钮扣电极所设计的一套模拟实验标定装置；着重介绍了钮扣电极测量束流位置的实验过程，以及在实验中所遇到的问题和对实验平台所做的改进。实验表明钮扣电极对束流位置的测量精度达到亚mm量级，对于束位置偏心测量的相对误差范围在10％以内。     

基于束流位置探测器的束团长度测量

分析了驱动电子束团的频域特性,研究了基于该特性进行长度测量的理论基础;使用三维模拟软件对束流位置探测器(BPM)进行建模,用模拟的方法对传输阻抗进行了数值计算;对不同长度的束团进行了测量和计算,并且分析了束团位置在真空管道中偏移对束团长度测量的影响。由测量结果可见,电子束团长度在10~100 ps(3~30 mm)时,测量误差均小于2%,满足中国工程物理研究院高平均功率自由电子激光太赫兹实验测量的使用要求。     

声速测量装置的改进

采用低频数字信号源推动小型扬声器做声源,用静电式驻极体传感器做拾音器,对传统的声速测量装置进行了改进.改进后的装置不仅能测量不同频率的声速,而且又降低了成本.本文详细介绍了电路的组成及测量结果.     

关于"太阳在银河系中所受引力与到银心距离r的关系"的讨论

讨论了银道面内的引力场强分布和太阳在银河系中所受引力与到银心距离r的关系，指出引力场强g并不是与r的平方成反比，这是由于银河系的大小和形状不能忽略造成的．强调了万有引力定律的适用条件．     

On the predictability of the positions of the convergence zones in the ocean

The disagreement between the experimental and calculated positions of the first convergence zone are known from many publications. The most probable cause for such a disagreement, namely, the incorrect specification of the input data for the calculations, is considered. The lack of simultaneity between the hydrological surveys of the region and the acoustic experiments is emphasized. The experimental data obtained by the author in five ocean regions are presented. These data characterize the diurnal variability of the distance from the source to the nearest boundary of the convergence zone. The relations proposed by different researchers for calculating the sound speed from the temperature, salinity, and hydrostatic pressure are analyzed. It is shown that these relations lead to a substantial difference in the estimated depth dependence of the hydrostatic gradient of the sound speed. The position of the first convergence zone is calculated for the propagation conditions determined by vertical temperature and salinity profiles with the subsequent recalculation of these profiles into sound speed profiles by using eight different formulas known from the literature. It is shown that different formulas lead to different values of the distance to the first zone; this difference is substantially greater than that between the calculations and experiment. The necessity of improving the recalculation relations in view of the experimental data on sound propagation in natural oceanic waveguides, including the data on the actual positions of the convergence zones, is emphasized.     

On the calculation of the bremsstrahlung in the region of the plasma frequency

On the basis of the classical theory of radiation produced in incomplete Coulomb interaction, a formula is derived for the coefficient of the bremsstrahlung of fully ionized plasma. In the region of rectilinear approximation a comparison is made with the results of the quantum formula derived from the Born approximation. Furthermore, the influence of dispersion upon the emission coefficient is taken into account; some relations for the region of dispersion are given.     

Dependence of the Intensity of the Spectral Lines and the Composition of the Sample and the Plasma Parameters of the Unipolar Arc

The investigation was made of the dependence of the intensity of Tl, Ga, Mo, Mg, Mn, Sn, Bi, Ni, Zn, Pt and Au spectral lines and the plasma parameters (temperature T, electron concentration n_e, degree of 6 ionnization α) from concentration of lithium additive.     

Extracting the wavefunction of the LSP at the LHC

We consider associated production of squarks and gluinos with the lightest supersymmetric particle (LSP), or states nearly degenerate in mass with it. Though sub-dominant to pair production of color SU(3)-charged superpartners, these processes are directly sensitive to the wavefunction composition of the lightest neutralinos. Exploiting event-shape variables - including some introduced here for the first time - we are able to identify the composition of the LSP by selecting events involving a single high-pT jet recoiling against missing transverse energy. We illustrate the proposed technique on a set of benchmark cases and propose methods for applying these results in more realistic experimental environments.     

Set the controls for the heart of the Sun

In this paper we describe experiments conducted with high-power lasers that are attempting to replicate, for a very short time and in miniature, conditions found in the Sun. Experiments to date have reached conditions in the outer part of the Sun. To reach the Sun's centre requires compression of material to very much greater than solid density and heating to over ten million degrees. To achieve this, a new class of experiments and a new generation of high-power lasers are required.     

On the Question of the Source of the Apokamp

Technical Physics - The object of this work is the apokamp—a new type of plasma jet, which is formed from a bright offshoot emerging at the bending point of a channel of a high-voltage...