热声驱动系统中的压力测量

介绍了自制的用于热声驱动脉管制冷装置的计算机压力波数据采集系统。该系统由硅压电压力传感器、数据采集卡、PC机和基于 Labview软件的图形化用户界面 GUI( Graphical User In-terface)组成。试验证明 ,它具有结构简单、高效精确、操作简便等特点 ,在捕捉被测系统内的动态压力变化方面具有优势 ,不但能很好地满足热声驱动器的压力测量要求 ,而且亦可移植到任何类似的测量气体压力的场合     

N2（A）及N（2D）对IF（X）的传能研究

在微波放电系统中,对NH_3-F-F_2-CF_3I体系进行研究,结果表明,向IF(X)传能的诸多媒介中,N_2(A)及N(~2D)起着主要作用,并且这一结论在经微波激发后的N_2与CF_3I的直接反应中得到了进一步证实。     

Low-Temperature Growth of Polycrystalline silicon Films by SiCl4／H2 rf Plasma Enhanced Chemical Vapour Deposition

Polycrystalline silicon film was directly fabricated at 200℃ by the conventional plasma enhanced chemical vapour deposition method from SiCl4 with H2 dilution. The crystallization depends strongly on the deposition power.The maximum crystMlinity and the crystalline grain size are over 80% and 200—50Onm, respectively. The results of energy dispersive spectroscopy and infrared spectroscopy measurements demonstrate that the film is mostly composed of silicon, without impurities such as Cl, N, C and bonded H. It is suggested that the crystallization at such a low temperature originates from the effects of chlorine, i.e., in-situ chemical, etching, in-situ chemical cleaning, and the detachment of bonded H.     

Residual stress profiling of an aluminum alloy by laser ultrasonics

A residual-stress profile along the thickness of an aluminum alloy sheet is determined by laser-ultrasonic technique. Surface acoustic waves are generated by a Nd:YAG pulse laser and detected by a Heterodyne interferometer on a lateral free surface of the sheet. The distribution of residual stress is determined by measuring the relative variation of the wavevelocities at different location of the sample along its thickness. This technique is validated by three different residual stress profiles obtained experimentally.     

更快、更高、更强——2001年的超导研究

 在2001年,全世界的科技工作者为量子论诞生100周年和诺贝尔奖颁发100周年举行了一系列庆祝活动。在《科学美国人》杂志的一篇纪念文章中,作者列举了33项展示量子论神奇力量的重大发现,这其中有8项与超流-凝聚有关。它们是1911年超导电性的发现,1924年玻色-爱因斯坦凝聚(BEC)的预言,1938年超流的发现,1957年BCS超导理论的提出,1973年核磁共振成像用于医疗诊断,1980和1982年整数和分数量子霍尔效应的发现,1986年铜氧化物高温超导体的发现和1995年BEC的实现。     

光辅助超高真空CVD系统制备SiGe异质结双极晶体管研究

介绍了采用紫外光化学汽相淀积(UVCVD)、超高真空化学汽相淀积(UHVCVD)和超低压化学汽相淀积(ULPCVD)技术研制的化学汽相淀积(CVD)工艺系统,简称U³CVD系统.应用该系统,在450℃低温和10^-7Pa超高真空环境下研制出了硅锗(SiGe)材料和硅锗异质结双极晶体管(SiGe HBT)材料.实验表明,该系统制备的SiGe HBT材料性能良好.