High performance streaked X-ray spectrometer for research of laser-produced plasmas

In order to mitigate the effect of the strong electromagnetic pulse, which produces laser-plasma interactions, we designed a new streaked X-ray spectrometer （SXS） enclosed within a well-sealed, electromag- netic interference-free cavity. The SXS can cover a wide selection of spectral windows using interchangeable Bragg crystals and by appropriate adjustment of the Bragg angle. The SXS has been used to observe time-re- solved X-ray spectrum in the 2.5 keV to 3.5 keV photon-energy range, resulting in a demonstrated spectral res- olution of about 13 at 2960 eV with a time resolution of 10 ps. The observed time and spectral resolutions dem- onstrate the applicability of the SXS for studies of laser-produced plasmas.

基于压电晶体的声波激励小型化低频天线技术研究

水下信息实时传输的需求与日俱增,水声通信和光通信等传统通信手段在传输安全性与稳定性方面具有先天难以弥补的劣势,且在传输速率方面难以形成突破,因此亟待对新技术进行研究。为解决此问题,近年一些学者提出一种新机理、新材料和新工艺的小型化天线,有望实现低频天线在尺寸和性能上的跨越,实现水下通信技术的变革。该文对此类声波激励小型化天线进行研究。首先阐述并建立了天线辐射机理及理论模型,分析了不同材料参数对天线性能的影响;然后根据模型参数设计加工了基于铌酸锂(LiNbO_(3))晶体的压电型声波激励天线样机,实验结果表明在40.83 kHz谐振频率处,与同尺寸单极子天线相比,其接收电压峰值为后者的22倍,辐射效率为400多倍;最后对天线进行了方位测试和辐射效率计算。上述结果表明:基于压电晶体的声波激励天线技术在低频段小型化、机动化水下无线通信设备的应用中具有巨大潜力。